[Sync] Remove backup/rollback logic from Sync

BUG=586596

Review URL: https://codereview.chromium.org/1703173002

Cr-Commit-Position: refs/heads/master@{#377370}

79 files changed, 68 insertions, 3483 deletions

diff --git a/chrome/browser/prefs/chrome_pref_service_factory.cc b/chrome/browser/prefs/chrome_pref_service_factory.cc
index 15539f8..2472dee 100644
--- a/chrome/browser/prefs/chrome_pref_service_factory.cc
+++ b/chrome/browser/prefs/chrome_pref_service_factory.cc
@@ -193,12 +193,8 @@ const PrefHashFilter::TrackedPreferenceMetadata kTrackedPrefs[] = {
     PrefHashFilter::TRACKING_STRATEGY_ATOMIC,
     PrefHashFilter::VALUE_IMPERSONAL
   },
-  {
-    17, sync_driver::prefs::kSyncRemainingRollbackTries,
-    PrefHashFilter::ENFORCE_ON_LOAD,
-    PrefHashFilter::TRACKING_STRATEGY_ATOMIC,
-    PrefHashFilter::VALUE_IMPERSONAL
-  },
+  // kSyncRemainingRollbackTries is deprecated and will be removed a few
+  // releases after M50.
   {
     18, prefs::kSafeBrowsingIncidentsSent,
     PrefHashFilter::ENFORCE_ON_LOAD,
diff --git a/chrome/browser/supervised_user/supervised_user_service.cc b/chrome/browser/supervised_user/supervised_user_service.cc
index c0f01fb..260752f 100644
--- a/chrome/browser/supervised_user/supervised_user_service.cc
+++ b/chrome/browser/supervised_user/supervised_user_service.cc
@@ -674,8 +674,7 @@ void SupervisedUserService::FinishSetupSyncWhenReady() {
   // Continue in FinishSetupSync() once the Sync backend has been initialized.
   ProfileSyncService* service =
       ProfileSyncServiceFactory::GetForProfile(profile_);
-  if (service->IsBackendInitialized() &&
-      service->backend_mode() == ProfileSyncService::SYNC) {
+  if (service->IsBackendInitialized()) {
     FinishSetupSync();
   } else {
     service->AddObserver(this);
@@ -687,7 +686,6 @@ void SupervisedUserService::FinishSetupSync() {
   ProfileSyncService* service =
       ProfileSyncServiceFactory::GetForProfile(profile_);
   DCHECK(service->IsBackendInitialized());
-  DCHECK(service->backend_mode() == ProfileSyncService::SYNC);
 
   // Sync nothing (except types which are set via GetPreferredDataTypes).
   bool sync_everything = false;
@@ -1023,8 +1021,7 @@ syncer::ModelTypeSet SupervisedUserService::GetPreferredDataTypes() const {
 void SupervisedUserService::OnStateChanged() {
   ProfileSyncService* service =
       ProfileSyncServiceFactory::GetForProfile(profile_);
-  if (waiting_for_sync_initialization_ && service->IsBackendInitialized() &&
-      service->backend_mode() == ProfileSyncService::SYNC) {
+  if (waiting_for_sync_initialization_ && service->IsBackendInitialized()) {
     waiting_for_sync_initialization_ = false;
     service->RemoveObserver(this);
     FinishSetupSync();
diff --git a/chrome/browser/sync/chrome_sync_client.cc b/chrome/browser/sync/chrome_sync_client.cc
index 661ca35..0327706 100644
--- a/chrome/browser/sync/chrome_sync_client.cc
+++ b/chrome/browser/sync/chrome_sync_client.cc
@@ -12,8 +12,6 @@
 #include "build/build_config.h"
 #include "chrome/browser/autofill/personal_data_manager_factory.h"
 #include "chrome/browser/bookmarks/bookmark_model_factory.h"
-#include "chrome/browser/browsing_data/browsing_data_helper.h"
-#include "chrome/browser/browsing_data/browsing_data_remover_factory.h"
 #include "chrome/browser/dom_distiller/dom_distiller_service_factory.h"
 #include "chrome/browser/favicon/favicon_service_factory.h"
 #include "chrome/browser/history/history_service_factory.h"
@@ -248,12 +246,6 @@ autofill::PersonalDataManager* ChromeSyncClient::GetPersonalDataManager() {
   return autofill::PersonalDataManagerFactory::GetForProfile(profile_);
 }
 
-sync_driver::ClearBrowsingDataCallback
-ChromeSyncClient::GetClearBrowsingDataCallback() {
-  return base::Bind(&ChromeSyncClient::ClearBrowsingData,
-                    base::Unretained(this));
-}
-
 base::Closure ChromeSyncClient::GetPasswordStateChangedCallback() {
   return base::Bind(
       &PasswordStoreFactory::OnPasswordsSyncedStatePotentiallyChanged,
@@ -484,28 +476,6 @@ ChromeSyncClient::GetSyncApiComponentFactory() {
   return component_factory_.get();
 }
 
-void ChromeSyncClient::ClearBrowsingData(base::Time start, base::Time end) {
-  BrowsingDataRemover* remover =
-      BrowsingDataRemoverFactory::GetForBrowserContext(profile_);
-  remover->Remove(BrowsingDataRemover::TimeRange(start, end),
-                  BrowsingDataRemover::REMOVE_ALL, BrowsingDataHelper::ALL);
-
-  password_store_->RemoveLoginsSyncedBetween(start, end);
-}
-
-void ChromeSyncClient::SetBrowsingDataRemoverObserverForTesting(
-    BrowsingDataRemover::Observer* observer) {
-  BrowsingDataRemover* remover =
-      BrowsingDataRemoverFactory::GetForBrowserContext(profile_);
-  if (browsing_data_remover_observer_)
-    remover->RemoveObserver(browsing_data_remover_observer_);
-
-  if (observer)
-    remover->AddObserver(observer);
-
-  browsing_data_remover_observer_ = observer;
-}
-
 void ChromeSyncClient::SetSyncApiComponentFactoryForTesting(
     scoped_ptr<sync_driver::SyncApiComponentFactory> component_factory) {
   component_factory_ = std::move(component_factory);
diff --git a/chrome/browser/sync/chrome_sync_client.h b/chrome/browser/sync/chrome_sync_client.h
index 4e58821..f94c669 100644
--- a/chrome/browser/sync/chrome_sync_client.h
+++ b/chrome/browser/sync/chrome_sync_client.h
@@ -39,8 +39,6 @@ class ChromeSyncClient : public sync_driver::SyncClient {
   bookmarks::BookmarkModel* GetBookmarkModel() override;
   favicon::FaviconService* GetFaviconService() override;
   history::HistoryService* GetHistoryService() override;
-  sync_driver::ClearBrowsingDataCallback GetClearBrowsingDataCallback()
-      override;
   base::Closure GetPasswordStateChangedCallback() override;
   sync_driver::SyncApiComponentFactory::RegisterDataTypesMethod
   GetRegisterPlatformTypesCallback() override;
@@ -79,8 +77,6 @@ class ChromeSyncClient : public sync_driver::SyncClient {
                                 syncer::ModelTypeSet disabled_types,
                                 syncer::ModelTypeSet enabled_types);
 
-  void ClearBrowsingData(base::Time start, base::Time end);
-
   Profile* const profile_;
 
   // The sync api component factory in use by this client.
diff --git a/chrome/browser/sync/test/integration/profile_sync_service_harness.cc b/chrome/browser/sync/test/integration/profile_sync_service_harness.cc
index f285656..7cf94c8 100644
--- a/chrome/browser/sync/test/integration/profile_sync_service_harness.cc
+++ b/chrome/browser/sync/test/integration/profile_sync_service_harness.cc
@@ -56,8 +56,6 @@ class BackendInitializeChecker : public SingleClientStatusChangeChecker {
       : SingleClientStatusChangeChecker(service) {}
 
   bool IsExitConditionSatisfied() override {
-    if (service()->backend_mode() != ProfileSyncService::SYNC)
-      return false;
     if (service()->IsBackendInitialized())
       return true;
     // Backend initialization is blocked by an auth error.
diff --git a/chrome/browser/sync/test/integration/single_client_backup_rollback_test.cc b/chrome/browser/sync/test/integration/single_client_backup_rollback_test.cc
deleted file mode 100644
index 90f7841..0000000
--- a/chrome/browser/sync/test/integration/single_client_backup_rollback_test.cc
+++ /dev/null
@@ -1,451 +0,0 @@
-// Copyright 2014 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "base/command_line.h"
-#include "base/files/file_util.h"
-#include "base/location.h"
-#include "base/macros.h"
-#include "base/run_loop.h"
-#include "base/single_thread_task_runner.h"
-#include "base/test/test_timeouts.h"
-#include "base/thread_task_runner_handle.h"
-#include "chrome/browser/browsing_data/browsing_data_remover.h"
-#include "chrome/browser/profiles/profile.h"
-#include "chrome/browser/sync/chrome_sync_client.h"
-#include "chrome/browser/sync/test/integration/bookmarks_helper.h"
-#include "chrome/browser/sync/test/integration/preferences_helper.h"
-#include "chrome/browser/sync/test/integration/sync_integration_test_util.h"
-#include "chrome/browser/sync/test/integration/sync_test.h"
-#include "components/bookmarks/browser/bookmark_model.h"
-#include "components/browser_sync/browser/profile_sync_service.h"
-#include "components/prefs/pref_service.h"
-#include "components/sync_driver/sync_driver_features.h"
-#include "components/sync_driver/sync_driver_switches.h"
-#include "sync/internal_api/public/util/sync_db_util.h"
-#include "sync/test/fake_server/fake_server_verifier.h"
-#include "sync/util/time.h"
-
-using bookmarks::BookmarkNode;
-using bookmarks_helper::AddFolder;
-using bookmarks_helper::AddURL;
-using bookmarks_helper::GetOtherNode;
-using bookmarks_helper::ModelMatchesVerifier;
-using bookmarks_helper::Move;
-using bookmarks_helper::Remove;
-using sync_integration_test_util::AwaitCommitActivityCompletion;
-
-namespace {
-const char kUrl1[] = "http://www.google.com";
-const char kUrl2[] = "http://map.google.com";
-const char kUrl3[] = "http://plus.google.com";
-}  // anonymous namespace
-
-class SingleClientBackupRollbackTest : public SyncTest {
- public:
-  SingleClientBackupRollbackTest() : SyncTest(SINGLE_CLIENT) {}
-  ~SingleClientBackupRollbackTest() override {}
-
-  void DisableBackup() {
-    base::CommandLine::ForCurrentProcess()->AppendSwitch(
-        switches::kSyncDisableBackup);
-  }
-
-  void DisableRollback() {
-    base::CommandLine::ForCurrentProcess()->AppendSwitch(
-        switches::kSyncDisableRollback);
-  }
-
-  base::Time GetBackupDbLastModified() {
-    base::RunLoop run_loop;
-
-    base::Time backup_time;
-    syncer::CheckSyncDbLastModifiedTime(
-        GetProfile(0)->GetPath().Append(FILE_PATH_LITERAL("Sync Data Backup")),
-        base::ThreadTaskRunnerHandle::Get(),
-        base::Bind(&SingleClientBackupRollbackTest::CheckDbCallback,
-                   base::Unretained(this), &backup_time));
-    base::ThreadTaskRunnerHandle::Get()->PostTask(
-        FROM_HERE, run_loop.QuitClosure());
-    run_loop.Run();
-    return backup_time;
-  }
-
- private:
-  void CheckDbCallback(base::Time* time_out, base::Time time_in) {
-    *time_out = syncer::ProtoTimeToTime(syncer::TimeToProtoTime(time_in));
-  }
-
-  DISALLOW_COPY_AND_ASSIGN(SingleClientBackupRollbackTest);
-};
-
-// Waits until the ProfileSyncService's backend is in IDLE mode.
-class SyncBackendStoppedChecker : public sync_driver::SyncServiceObserver {
- public:
-  explicit SyncBackendStoppedChecker(ProfileSyncService* service)
-      : pss_(service),
-        timeout_(TestTimeouts::action_max_timeout()),
-        done_(false) {}
-
-  void OnStateChanged() override {
-    if (ProfileSyncService::IDLE == pss_->backend_mode()) {
-      done_ = true;
-      run_loop_.Quit();
-    }
-  }
-
-  bool Wait() {
-    pss_->AddObserver(this);
-    if (ProfileSyncService::IDLE == pss_->backend_mode())
-      return true;
-    base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
-        FROM_HERE, run_loop_.QuitClosure(), timeout_);
-    run_loop_.Run();
-    pss_->RemoveObserver(this);
-    return done_;
-  }
-
- private:
-
-  ProfileSyncService* const pss_;
-  const base::TimeDelta timeout_;
-  base::RunLoop run_loop_;
-  bool done_;
-};
-
-// Waits until a rollback finishes.
-class SyncRollbackChecker : public sync_driver::SyncServiceObserver,
-                            public BrowsingDataRemover::Observer {
- public:
-  explicit SyncRollbackChecker(ProfileSyncService* service)
-      : pss_(service),
-        timeout_(TestTimeouts::action_max_timeout()),
-        rollback_started_(false),
-        clear_done_(false) {}
-
-  // sync_driver::SyncServiceObserver implementation.
-  void OnStateChanged() override {
-    if (ProfileSyncService::ROLLBACK == pss_->backend_mode()) {
-      rollback_started_ = true;
-      if (clear_done_)
-        run_loop_.Quit();
-    }
-  }
-
-  // BrowsingDataRemoverObserver::Observer implementation.
-  void OnBrowsingDataRemoverDone() override {
-    // Remove ourselves as an observer.
-    browser_sync::ChromeSyncClient* sync_client =
-        static_cast<browser_sync::ChromeSyncClient*>(pss_->GetSyncClient());
-    sync_client->SetBrowsingDataRemoverObserverForTesting(nullptr);
-
-    clear_done_ = true;
-    if (rollback_started_) {
-      run_loop_.Quit();
-    }
-  }
-
-  bool Wait() {
-    pss_->AddObserver(this);
-
-    browser_sync::ChromeSyncClient* sync_client =
-        static_cast<browser_sync::ChromeSyncClient*>(pss_->GetSyncClient());
-    sync_client->SetBrowsingDataRemoverObserverForTesting(this);
-    base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
-        FROM_HERE, run_loop_.QuitClosure(), timeout_);
-    run_loop_.Run();
-    pss_->RemoveObserver(this);
-    return rollback_started_ && clear_done_;
-  }
-
-  ProfileSyncService* const pss_;
-  const base::TimeDelta timeout_;
-  base::RunLoop run_loop_;
-  bool rollback_started_;
-  bool clear_done_;
-};
-
-#if BUILDFLAG(ENABLE_PRE_SYNC_BACKUP)
-#define MAYBE_TestBackup TestBackup
-#else
-#define MAYBE_TestBackup DISABLED_TestBackup
-#endif
-IN_PROC_BROWSER_TEST_F(SingleClientBackupRollbackTest,
-                       MAYBE_TestBackup) {
-  ASSERT_TRUE(SetupClients()) << "SetupClients() failed.";
-
-  // Setup sync, wait for its completion, and make sure changes were synced.
-  ASSERT_TRUE(SetupSync()) << "SetupSync() failed.";
-  ASSERT_TRUE(AwaitCommitActivityCompletion(GetSyncService(0)));
-  ASSERT_TRUE(ModelMatchesVerifier(0));
-
-  // Verify backup DB is created and backup time is set on device info.
-  base::Time backup_time = GetBackupDbLastModified();
-  ASSERT_FALSE(backup_time.is_null());
-  ASSERT_EQ(backup_time, GetSyncService(0)->GetDeviceBackupTimeForTesting());
-}
-
-#if BUILDFLAG(ENABLE_PRE_SYNC_BACKUP)
-#define MAYBE_TestBackupDisabled TestBackupDisabled
-#else
-#define MAYBE_TestBackupDisabled DISABLED_TestBackupDisabled
-#endif
-IN_PROC_BROWSER_TEST_F(SingleClientBackupRollbackTest,
-                       MAYBE_TestBackupDisabled) {
-  DisableBackup();
-
-  // Setup sync, wait for its completion, and make sure changes were synced.
-  ASSERT_TRUE(SetupSync()) << "SetupSync() failed.";
-  ASSERT_TRUE(AwaitCommitActivityCompletion(GetSyncService(0)));
-  ASSERT_TRUE(ModelMatchesVerifier(0));
-
-  // Verify backup DB is not created and backup time is not set on device info.
-  ASSERT_FALSE(base::PathExists(
-      GetProfile(0)->GetPath().Append(FILE_PATH_LITERAL("Sync Data Backup"))));
-  ASSERT_TRUE(GetSyncService(0)->GetDeviceBackupTimeForTesting().is_null());
-}
-
-#if BUILDFLAG(ENABLE_PRE_SYNC_BACKUP)
-#define MAYBE_TestRollback TestRollback
-#else
-#define MAYBE_TestRollback DISABLED_TestRollback
-#endif
-IN_PROC_BROWSER_TEST_F(SingleClientBackupRollbackTest,
-                       MAYBE_TestRollback) {
-  ASSERT_TRUE(SetupClients()) << "SetupClients() failed.";
-
-  // Starting state:
-  // other_node
-  //    -> top
-  //      -> tier1_a
-  //        -> http://mail.google.com  "tier1_a_url0"
-  //      -> tier1_b
-  //        -> http://www.nhl.com "tier1_b_url0"
-  const BookmarkNode* top = AddFolder(0, GetOtherNode(0), 0, "top");
-  const BookmarkNode* tier1_a = AddFolder(0, top, 0, "tier1_a");
-  const BookmarkNode* tier1_b = AddFolder(0, top, 1, "tier1_b");
-  ASSERT_TRUE(AddURL(0, tier1_a, 0, "tier1_a_url0",
-                     GURL("http://mail.google.com")));
-  ASSERT_TRUE(AddURL(0, tier1_b, 0, "tier1_b_url0",
-                     GURL("http://www.nhl.com")));
-
-  // Setup sync, wait for its completion, and make sure changes were synced.
-  ASSERT_TRUE(SetupSync()) << "SetupSync() failed.";
-  ASSERT_TRUE(AwaitCommitActivityCompletion(GetSyncService(0)));
-  ASSERT_TRUE(ModelMatchesVerifier(0));
-
-  // Made bookmark changes while sync is on.
-  Move(0, tier1_a->GetChild(0), tier1_b, 1);
-  Remove(0, tier1_b, 0);
-  ASSERT_TRUE(AddFolder(0, tier1_b, 1, "tier2_c"));
-  ASSERT_TRUE(AwaitCommitActivityCompletion(GetSyncService(0)));
-  ASSERT_TRUE(ModelMatchesVerifier(0));
-
-  // Let server to return rollback command on next sync request.
-  ASSERT_TRUE(GetFakeServer()->TriggerError(sync_pb::SyncEnums::USER_ROLLBACK));
-
-  // Make another change to trigger downloading of rollback command.
-  Remove(0, tier1_b, 0);
-
-  // Wait for rollback to finish and sync backend is completely shut down.
-  SyncRollbackChecker rollback_checker(GetSyncService(0));
-  ASSERT_TRUE(rollback_checker.Wait());
-  SyncBackendStoppedChecker shutdown_checker(GetSyncService(0));
-  ASSERT_TRUE(shutdown_checker.Wait());
-
-  // Verify bookmarks are restored.
-  ASSERT_EQ(1, tier1_a->child_count());
-  const BookmarkNode* url1 = tier1_a->GetChild(0);
-  ASSERT_EQ(GURL("http://mail.google.com"), url1->url());
-
-  ASSERT_EQ(1, tier1_b->child_count());
-  const BookmarkNode* url2 = tier1_b->GetChild(0);
-  ASSERT_EQ(GURL("http://www.nhl.com"), url2->url());
-}
-
-#if BUILDFLAG(ENABLE_PRE_SYNC_BACKUP)
-#define MAYBE_TestRollbackDisabled TestRollbackDisabled
-#else
-#define MAYBE_TestRollbackDisabled DISABLED_TestRollbackDisabled
-#endif
-IN_PROC_BROWSER_TEST_F(SingleClientBackupRollbackTest,
-                       MAYBE_TestRollbackDisabled) {
-  DisableRollback();
-
-  ASSERT_TRUE(SetupClients()) << "SetupClients() failed.";
-
-  // Starting state:
-  // other_node
-  //    -> http://mail.google.com  "url0"
-  //    -> http://www.nhl.com "url1"
-  ASSERT_TRUE(AddURL(0, GetOtherNode(0), 0, "url0",
-                     GURL("http://mail.google.com")));
-  ASSERT_TRUE(AddURL(0, GetOtherNode(0), 1, "url1",
-                     GURL("http://www.nhl.com")));
-
-  // Setup sync, wait for its completion, and make sure changes were synced.
-  ASSERT_TRUE(SetupSync()) << "SetupSync() failed.";
-  ASSERT_TRUE(AwaitCommitActivityCompletion(GetSyncService(0)));
-  ASSERT_TRUE(ModelMatchesVerifier(0));
-
-  // Made bookmark changes while sync is on.
-  Remove(0, GetOtherNode(0), 1);
-  ASSERT_TRUE(AddURL(0, GetOtherNode(0), 1, "url2",
-                     GURL("http://www.yahoo.com")));
-  ASSERT_TRUE(AwaitCommitActivityCompletion(GetSyncService((0))));
-  ASSERT_TRUE(ModelMatchesVerifier(0));
-
-  // Let server to return rollback command on next sync request.
-  ASSERT_TRUE(GetFakeServer()->TriggerError(sync_pb::SyncEnums::USER_ROLLBACK));
-
-  // Make another change to trigger downloading of rollback command.
-  Remove(0, GetOtherNode(0), 0);
-
-  // Wait for sync backend is completely shut down.
-  SyncBackendStoppedChecker shutdown_checker(GetSyncService(0));
-  ASSERT_TRUE(shutdown_checker.Wait());
-
-  // With rollback disabled, bookmarks in backup DB should not be restored.
-  // Only bookmark added during sync is present.
-  ASSERT_EQ(1, GetOtherNode(0)->child_count());
-  ASSERT_EQ(GURL("http://www.yahoo.com"),
-            GetOtherNode(0)->GetChild(0)->url());
-}
-
-#if BUILDFLAG(ENABLE_PRE_SYNC_BACKUP)
-#define MAYBE_TestSyncDisabled TestSyncDisabled
-#else
-#define MAYBE_TestSyncDisabled DISABLED_TestSyncDisabled
-#endif
-IN_PROC_BROWSER_TEST_F(SingleClientBackupRollbackTest,
-                       MAYBE_TestSyncDisabled) {
-  ASSERT_TRUE(SetupClients()) << "SetupClients() failed.";
-
-  // Starting state:
-  // other_node
-  //    -> http://mail.google.com  "url0"
-  //    -> http://www.nhl.com "url1"
-  ASSERT_TRUE(AddURL(0, GetOtherNode(0), 0, "url0",
-                     GURL("http://mail.google.com")));
-  ASSERT_TRUE(AddURL(0, GetOtherNode(0), 1, "url1",
-                     GURL("http://www.nhl.com")));
-
-  // Setup sync, wait for its completion, and make sure changes were synced.
-  ASSERT_TRUE(SetupSync()) << "SetupSync() failed.";
-  ASSERT_TRUE(AwaitCommitActivityCompletion(GetSyncService(0)));
-  ASSERT_TRUE(ModelMatchesVerifier(0));
-
-  // Made bookmark changes while sync is on.
-  Remove(0, GetOtherNode(0), 1);
-  ASSERT_TRUE(AddURL(0, GetOtherNode(0), 1, "url2",
-                     GURL("http://www.yahoo.com")));
-  ASSERT_TRUE(AwaitCommitActivityCompletion(GetSyncService((0))));
-  ASSERT_TRUE(ModelMatchesVerifier(0));
-
-  // Let server to return birthday error on next sync request.
-  ASSERT_TRUE(GetFakeServer()->TriggerError(
-      sync_pb::SyncEnums::NOT_MY_BIRTHDAY));
-
-  // Make another change to trigger downloading of rollback command.
-  Remove(0, GetOtherNode(0), 0);
-
-  // Wait sync backend is completely shut down.
-  SyncBackendStoppedChecker shutdown_checker(GetSyncService(0));
-  ASSERT_TRUE(shutdown_checker.Wait());
-
-  // Shouldn't restore bookmarks with sign-out only.
-  ASSERT_EQ(1, GetOtherNode(0)->child_count());
-  ASSERT_EQ(GURL("http://www.yahoo.com"),
-            GetOtherNode(0)->GetChild(0)->url());
-}
-
-#if BUILDFLAG(ENABLE_PRE_SYNC_BACKUP)
-#define MAYBE_RollbackNoBackup RollbackNoBackup
-#else
-#define MAYBE_RollbackNoBackup DISABLED_RollbackNoBackup
-#endif
-IN_PROC_BROWSER_TEST_F(SingleClientBackupRollbackTest,
-                       MAYBE_RollbackNoBackup) {
-  ASSERT_TRUE(SetupClients()) << "SetupClients() failed.";
-
-  // Starting state:
-  // other_node
-  //    -> http://mail.google.com  "url0"
-  //    -> http://www.nhl.com "url1"
-  ASSERT_TRUE(AddURL(0, GetOtherNode(0), 0, "url0",
-                     GURL("http://mail.google.com")));
-
-  // Setup sync, wait for its completion, and make sure changes were synced.
-  ASSERT_TRUE(SetupSync()) << "SetupSync() failed.";
-  ASSERT_TRUE(AwaitCommitActivityCompletion(GetSyncService((0))));
-  ASSERT_TRUE(ModelMatchesVerifier(0));
-
-  ASSERT_TRUE(AddURL(0, GetOtherNode(0), 1, "url1",
-                     GURL("http://www.nhl.com")));
-
-  // Delete backup DB.
-  base::DeleteFile(
-      GetProfile(0)->GetPath().Append(FILE_PATH_LITERAL("Sync Data Backup")),
-      true);
-
-  // Let server to return rollback command on next sync request.
-  ASSERT_TRUE(GetFakeServer()->TriggerError(sync_pb::SyncEnums::USER_ROLLBACK));
-
-  // Make another change to trigger downloading of rollback command.
-  Remove(0, GetOtherNode(0), 0);
-
-  // Wait for rollback to finish and sync backend is completely shut down.
-  SyncRollbackChecker rollback_checker(GetSyncService(0));
-  ASSERT_TRUE(rollback_checker.Wait());
-  SyncBackendStoppedChecker checker(GetSyncService(0));
-  ASSERT_TRUE(checker.Wait());
-
-  // Without backup DB, bookmarks remain at the state when sync stops.
-  ASSERT_EQ(1, GetOtherNode(0)->child_count());
-  ASSERT_EQ(GURL("http://www.nhl.com"),
-            GetOtherNode(0)->GetChild(0)->url());
-}
-
-#if BUILDFLAG(ENABLE_PRE_SYNC_BACKUP)
-#define MAYBE_DontChangeBookmarkOrdering DontChangeBookmarkOrdering
-#else
-#define MAYBE_DontChangeBookmarkOrdering DISABLED_DontChangeBookmarkOrdering
-#endif
-IN_PROC_BROWSER_TEST_F(SingleClientBackupRollbackTest,
-                       MAYBE_DontChangeBookmarkOrdering) {
-  ASSERT_TRUE(SetupClients()) << "SetupClients() failed.";
-
-  const BookmarkNode* sub_folder = AddFolder(0, GetOtherNode(0), 0, "test");
-  ASSERT_TRUE(AddURL(0, sub_folder, 0, "", GURL(kUrl1)));
-  ASSERT_TRUE(AddURL(0, sub_folder, 1, "", GURL(kUrl2)));
-  ASSERT_TRUE(AddURL(0, sub_folder, 2, "", GURL(kUrl3)));
-
-  // Setup sync, wait for its completion, and make sure changes were synced.
-  ASSERT_TRUE(SetupSync()) << "SetupSync() failed.";
-  ASSERT_TRUE(AwaitCommitActivityCompletion(GetSyncService(0)));
-  ASSERT_TRUE(ModelMatchesVerifier(0));
-
-  // Made bookmark changes while sync is on.
-  Remove(0, sub_folder, 0);
-  Remove(0, sub_folder, 0);
-  ASSERT_TRUE(AwaitCommitActivityCompletion(GetSyncService(0)));
-  ASSERT_TRUE(ModelMatchesVerifier(0));
-
-  // Let server to return rollback command on next sync request.
-  ASSERT_TRUE(GetFakeServer()->TriggerError(sync_pb::SyncEnums::USER_ROLLBACK));
-
-  // Make another change to trigger downloading of rollback command.
-  Remove(0, sub_folder, 0);
-
-  // Wait for rollback to finish and sync backend is completely shut down.
-  SyncRollbackChecker rollback_checker(GetSyncService(0));
-  ASSERT_TRUE(rollback_checker.Wait());
-  SyncBackendStoppedChecker shutdown_checker(GetSyncService(0));
-  ASSERT_TRUE(shutdown_checker.Wait());
-
-  // Verify bookmarks are unchanged.
-  ASSERT_EQ(3, sub_folder->child_count());
-  ASSERT_EQ(GURL(kUrl1), sub_folder->GetChild(0)->url());
-  ASSERT_EQ(GURL(kUrl2), sub_folder->GetChild(1)->url());
-  ASSERT_EQ(GURL(kUrl3), sub_folder->GetChild(2)->url());
-}
diff --git a/chrome/chrome_tests.gypi b/chrome/chrome_tests.gypi
index 87bfb56..c67fd7c 100644
--- a/chrome/chrome_tests.gypi
+++ b/chrome/chrome_tests.gypi
@@ -1445,7 +1445,6 @@
       'browser/sync/test/integration/migration_test.cc',
       'browser/sync/test/integration/single_client_app_list_sync_test.cc',
       'browser/sync/test/integration/single_client_apps_sync_test.cc',
-      'browser/sync/test/integration/single_client_backup_rollback_test.cc',
       'browser/sync/test/integration/single_client_bookmarks_sync_test.cc',
       'browser/sync/test/integration/single_client_dictionary_sync_test.cc',
       'browser/sync/test/integration/single_client_directory_sync_test.cc',
diff --git a/chrome/chrome_tests_unit.gypi b/chrome/chrome_tests_unit.gypi
index 6d1fe03..491b995 100644
--- a/chrome/chrome_tests_unit.gypi
+++ b/chrome/chrome_tests_unit.gypi
@@ -2223,7 +2223,6 @@
         'test_support_unit',
         # 3) anything tests directly depend on
         '../components/components.gyp:generate_version_info',
-        '../components/components.gyp:sync_driver_features',
         '../courgette/courgette.gyp:courgette_lib',
         '../google_apis/google_apis.gyp:google_apis',
         '../skia/skia.gyp:skia',
diff --git a/components/browser_sync.gypi b/components/browser_sync.gypi
index 5c464060..b5bb383 100644
--- a/components/browser_sync.gypi
+++ b/components/browser_sync.gypi
@@ -31,7 +31,6 @@
         'syncable_prefs',
         'sync_bookmarks',
         'sync_driver',
-        'sync_driver_features',
         'sync_sessions',
         'variations',
         'version_info',
diff --git a/components/browser_sync/browser/profile_sync_components_factory_impl.cc b/components/browser_sync/browser/profile_sync_components_factory_impl.cc
index 9ce6b74..370c93e 100644
--- a/components/browser_sync/browser/profile_sync_components_factory_impl.cc
+++ b/components/browser_sync/browser/profile_sync_components_factory_impl.cc
@@ -331,7 +331,7 @@ ProfileSyncComponentsFactoryImpl::CreateAttachmentService(
   scoped_ptr<syncer::AttachmentDownloader> attachment_downloader;
   // Only construct an AttachmentUploader and AttachmentDownload if we have sync
   // credentials. We may not have sync credentials because there may not be a
-  // signed in sync user (e.g. sync is running in "backup" mode).
+  // signed in sync user.
   if (!user_share.sync_credentials.account_id.empty() &&
       !user_share.sync_credentials.scope_set.empty()) {
     scoped_refptr<OAuth2TokenServiceRequest::TokenServiceProvider>
diff --git a/components/browser_sync/browser/profile_sync_service.cc b/components/browser_sync/browser/profile_sync_service.cc
index 1fa9242..67987b2 100644
--- a/components/browser_sync/browser/profile_sync_service.cc
+++ b/components/browser_sync/browser/profile_sync_service.cc
@@ -51,7 +51,6 @@
 #include "components/sync_driver/signin_manager_wrapper.h"
 #include "components/sync_driver/sync_api_component_factory.h"
 #include "components/sync_driver/sync_client.h"
-#include "components/sync_driver/sync_driver_features.h"
 #include "components/sync_driver/sync_driver_switches.h"
 #include "components/sync_driver/sync_error_controller.h"
 #include "components/sync_driver/sync_stopped_reporter.h"
@@ -145,9 +144,6 @@ const net::BackoffEntry::Policy kRequestAccessTokenBackoffPolicy = {
 static const base::FilePath::CharType kSyncDataFolderName[] =
     FILE_PATH_LITERAL("Sync Data");
 
-static const base::FilePath::CharType kSyncBackupDataFolderName[] =
-    FILE_PATH_LITERAL("Sync Data Backup");
-
 namespace {
 
 // Perform the actual sync data folder deletion.
@@ -166,8 +162,6 @@ bool ShouldShowActionOnUI(
   return (error.action != syncer::UNKNOWN_ACTION &&
           error.action != syncer::DISABLE_SYNC_ON_CLIENT &&
           error.action != syncer::STOP_SYNC_FOR_DISABLED_ACCOUNT &&
-          error.action != syncer::DISABLE_SYNC_AND_ROLLBACK &&
-          error.action != syncer::ROLLBACK_DONE &&
           error.action != syncer::RESET_LOCAL_SYNC_DATA);
 }
 
@@ -224,9 +218,6 @@ ProfileSyncService::ProfileSyncService(InitParams init_params)
       last_get_token_error_(GoogleServiceAuthError::AuthErrorNone()),
       network_resources_(new syncer::HttpBridgeNetworkResources),
       start_behavior_(init_params.start_behavior),
-      backend_mode_(IDLE),
-      need_backup_(false),
-      backup_finished_(false),
       catch_up_configure_in_progress_(false),
       passphrase_prompt_triggered_by_version_(false),
       weak_factory_(this),
@@ -261,13 +252,7 @@ void ProfileSyncService::Initialize() {
   startup_controller_.reset(new browser_sync::StartupController(
       start_behavior_, oauth2_token_service_, &sync_prefs_, signin_.get(),
       base::Bind(&ProfileSyncService::StartUpSlowBackendComponents,
-                 startup_controller_weak_factory_.GetWeakPtr(), SYNC)));
-  backup_rollback_controller_.reset(new sync_driver::BackupRollbackController(
-      &sync_prefs_, signin_.get(),
-      base::Bind(&ProfileSyncService::StartUpSlowBackendComponents,
-                 startup_controller_weak_factory_.GetWeakPtr(), BACKUP),
-      base::Bind(&ProfileSyncService::StartUpSlowBackendComponents,
-                 startup_controller_weak_factory_.GetWeakPtr(), ROLLBACK)));
+                 startup_controller_weak_factory_.GetWeakPtr())));
   scoped_ptr<browser_sync::LocalSessionEventRouter> router(
       sync_client_->GetSyncSessionsClient()->GetLocalSessionEventRouter());
   local_device_ = sync_client_->GetSyncApiComponentFactory()
@@ -352,26 +337,6 @@ void ProfileSyncService::Initialize() {
   AddObserver(sync_error_controller_.get());
 #endif
 
-  bool running_rollback = false;
-  if (sync_driver::BackupRollbackController::IsBackupEnabled()) {
-    // Backup is needed if user's not signed in or signed in but previous
-    // backup didn't finish, i.e. backend didn't switch from backup to sync.
-    need_backup_ = !IsSignedIn() || sync_prefs_.GetFirstSyncTime().is_null();
-
-    // Try to resume rollback if it didn't finish in last session.
-    running_rollback = backup_rollback_controller_->StartRollback();
-  } else {
-    need_backup_ = false;
-  }
-
-#if BUILDFLAG(ENABLE_PRE_SYNC_BACKUP)
-  if (!running_rollback && !IsSignedIn()) {
-    CleanUpBackup();
-  }
-#else
-  DCHECK(!running_rollback);
-#endif
-
   memory_pressure_listener_.reset(new base::MemoryPressureListener(base::Bind(
       &ProfileSyncService::OnMemoryPressure, weak_factory_.GetWeakPtr())));
   startup_controller_->Reset(GetRegisteredDataTypes());
@@ -414,7 +379,6 @@ void ProfileSyncService::StartSyncingWithServer() {
 
   if (base::CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kSyncEnableClearDataOnPassphraseEncryption) &&
-      backend_mode_ == SYNC &&
       sync_prefs_.GetPassphraseEncryptionTransitionInProgress()) {
     BeginConfigureCatchUpBeforeClear();
     return;
@@ -494,34 +458,21 @@ void ProfileSyncService::OnSessionRestoreComplete() {
 
 SyncCredentials ProfileSyncService::GetCredentials() {
   SyncCredentials credentials;
-  if (backend_mode_ == SYNC) {
-    credentials.account_id = signin_->GetAccountIdToUse();
-    DCHECK(!credentials.account_id.empty());
-    credentials.email = signin_->GetEffectiveUsername();
-    credentials.sync_token = access_token_;
+  credentials.account_id = signin_->GetAccountIdToUse();
+  DCHECK(!credentials.account_id.empty());
+  credentials.email = signin_->GetEffectiveUsername();
+  credentials.sync_token = access_token_;
 
-    if (credentials.sync_token.empty())
-      credentials.sync_token = "credentials_lost";
+  if (credentials.sync_token.empty())
+    credentials.sync_token = "credentials_lost";
 
-    credentials.scope_set.insert(signin_->GetSyncScopeToUse());
-  }
+  credentials.scope_set.insert(signin_->GetSyncScopeToUse());
 
   return credentials;
 }
 
 bool ProfileSyncService::ShouldDeleteSyncFolder() {
-  switch (backend_mode_) {
-    case SYNC:
-      return !IsFirstSetupComplete();
-    case BACKUP:
-      return true;
-    case ROLLBACK:
-      return false;
-    case IDLE:
-      NOTREACHED();
-      return true;
-  }
-  return true;
+  return !IsFirstSetupComplete();
 }
 
 void ProfileSyncService::InitializeBackend(bool delete_stale_data) {
@@ -532,7 +483,7 @@ void ProfileSyncService::InitializeBackend(bool delete_stale_data) {
 
   SyncCredentials credentials = GetCredentials();
 
-  if (backend_mode_ == SYNC && delete_stale_data)
+  if (delete_stale_data)
     ClearStaleErrors();
 
   SyncBackendHost::HttpPostProviderFactoryGetter
@@ -547,7 +498,7 @@ void ProfileSyncService::InitializeBackend(bool delete_stale_data) {
       GetJsEventHandler(), sync_service_url_, local_device_->GetSyncUserAgent(),
       credentials, delete_stale_data,
       scoped_ptr<syncer::SyncManagerFactory>(
-          new syncer::SyncManagerFactory(GetManagerType())),
+          new syncer::SyncManagerFactory()),
       MakeWeakHandle(weak_factory_.GetWeakPtr()),
       base::Bind(browser_sync::ChromeReportUnrecoverableError, channel_),
       http_post_provider_factory_getter, std::move(saved_nigori_state_));
@@ -624,71 +575,11 @@ void ProfileSyncService::OnDataTypeRequestsSyncStartup(
   startup_controller_->OnDataTypeRequestsSyncStartup(type);
 }
 
-void ProfileSyncService::StartUpSlowBackendComponents(
-    ProfileSyncService::BackendMode mode) {
-  DCHECK_NE(IDLE, mode);
-  if (backend_mode_ == mode) {
-    return;
-  }
-
-  // Backend mode transition rules:
-  // * can transit from IDLE to any other non-IDLE mode.
-  // * forbidden to transit from SYNC to any other mode, i.e. SYNC backend must
-  //   be explicitly shut down before backup/rollback starts.
-  // * can not transit out of ROLLBACK mode until rollback is finished
-  //   (successfully or unsuccessfully).
-  // * can not transit out of BACKUP mode until backup is finished
-  //   (successfully or unsuccessfully).
-  // * if backup is needed, can only transit to SYNC if backup is finished,
-
-  if (backend_mode_ == SYNC) {
-    LOG(DFATAL) << "Shouldn't switch from mode SYNC to mode " << mode;
-    return;
-  }
-
-  if (backend_mode_ == ROLLBACK ||
-      (backend_mode_ == BACKUP && !backup_finished_)) {
-    // Wait for rollback/backup to finish before start new backend.
-    return;
-  }
-
-  if (mode == SYNC && NeedBackup() && !backup_finished_) {
-    if (backend_mode_ != BACKUP)
-      backup_rollback_controller_->StartBackup();
-    return;
-  }
-
-  DVLOG(1) << "Start backend mode: " << mode;
-
-  if (backend_) {
-    if (mode == SYNC)
-      ShutdownImpl(syncer::SWITCH_MODE_SYNC);
-    else
-      ShutdownImpl(syncer::STOP_SYNC);
-  }
-
-  backend_mode_ = mode;
-
-  if (backend_mode_ == BACKUP)
-    backup_start_time_ = base::Time::Now();
-
-  if (backend_mode_ == SYNC && !backup_start_time_.is_null()) {
-    UMA_HISTOGRAM_MEDIUM_TIMES("Sync.FirstSyncDelayByBackup",
-                               base::Time::Now() - backup_start_time_);
-    backup_start_time_ = base::Time();
-  }
-
-  if (backend_mode_ == ROLLBACK)
-    ClearBrowsingDataSinceFirstSync();
-  else if (backend_mode_ == SYNC)
-    CheckSyncBackupIfNeeded();
-
-  base::FilePath sync_folder = backend_mode_ == SYNC ?
-      base::FilePath(kSyncDataFolderName) :
-      base::FilePath(kSyncBackupDataFolderName);
+void ProfileSyncService::StartUpSlowBackendComponents() {
+  base::FilePath sync_folder = base::FilePath(kSyncDataFolderName);
 
   invalidation::InvalidationService* invalidator =
-      backend_mode_ == SYNC ? sync_client_->GetInvalidationService() : nullptr;
+      sync_client_->GetInvalidationService();
 
   directory_path_ = base_directory_.Append(sync_folder);
 
@@ -874,25 +765,9 @@ void ProfileSyncService::ShutdownImpl(syncer::ShutdownReason reason) {
 
   weak_factory_.InvalidateWeakPtrs();
 
-  if (backend_mode_ == SYNC)
-    startup_controller_->Reset(GetRegisteredDataTypes());
-
-  // Don't let backup block sync regardless backup succeeded or not.
-  if (backend_mode_ == BACKUP)
-    backup_finished_ = true;
-
-  // Sync could be blocked by rollback/backup. Post task to check whether sync
-  // should start after shutting down rollback/backup backend.
-  if ((backend_mode_ == ROLLBACK || backend_mode_ == BACKUP) &&
-      reason != syncer::SWITCH_MODE_SYNC &&
-      reason != syncer::BROWSER_SHUTDOWN) {
-    base::ThreadTaskRunnerHandle::Get()->PostTask(
-        FROM_HERE, base::Bind(&ProfileSyncService::TryStartSyncAfterBackup,
-                              startup_controller_weak_factory_.GetWeakPtr()));
-  }
+  startup_controller_->Reset(GetRegisteredDataTypes());
 
   // Clear various flags.
-  backend_mode_ = IDLE;
   expect_sync_configuration_aborted_ = false;
   is_auth_in_progress_ = false;
   backend_initialized_ = false;
@@ -1018,9 +893,6 @@ void ProfileSyncService::ReenableDatatype(syncer::ModelType type) {
 }
 
 void ProfileSyncService::UpdateBackendInitUMA(bool success) {
-  if (backend_mode_ != SYNC)
-    return;
-
   is_first_time_sync_configure_ = !IsFirstSetupComplete();
 
   if (is_first_time_sync_configure_) {
@@ -1040,14 +912,6 @@ void ProfileSyncService::UpdateBackendInitUMA(bool success) {
 }
 
 void ProfileSyncService::PostBackendInitialization() {
-  // Never get here for backup / restore.
-  DCHECK_EQ(backend_mode_, SYNC);
-
-  if (last_backup_time_) {
-    DCHECK(device_info_sync_service_);
-    device_info_sync_service_->UpdateLocalDeviceBackupTime(*last_backup_time_);
-  }
-
   if (protocol_event_observers_.might_have_observers()) {
     backend_->RequestBufferedProtocolEventsAndEnableForwarding();
   }
@@ -1129,10 +993,7 @@ void ProfileSyncService::OnBackendInitialized(
   local_device_->Initialize(cache_guid, signin_scoped_device_id,
                             blocking_pool_);
 
-  if (backend_mode_ == BACKUP || backend_mode_ == ROLLBACK)
-    ConfigureDataTypeManager();
-  else
-    PostBackendInitialization();
+  PostBackendInitialization();
 }
 
 void ProfileSyncService::OnSyncCycleCompleted() {
@@ -1370,9 +1231,6 @@ void ProfileSyncService::OnActionableError(const SyncProtocolError& error) {
                                    true,
                                    ERROR_REASON_ACTIONABLE_ERROR);
       break;
-    case syncer::DISABLE_SYNC_AND_ROLLBACK:
-      backup_rollback_controller_->OnRollbackReceived();
-      // Fall through to shutdown backend and sign user out.
     case syncer::DISABLE_SYNC_ON_CLIENT:
       if (error.error_type == syncer::NOT_MY_BIRTHDAY) {
         UMA_HISTOGRAM_ENUMERATION("Sync.StopSource", syncer::BIRTHDAY_ERROR,
@@ -1390,9 +1248,6 @@ void ProfileSyncService::OnActionableError(const SyncProtocolError& error) {
       }
 #endif
       break;
-    case syncer::ROLLBACK_DONE:
-      backup_rollback_controller_->OnRollbackDone();
-      break;
     case syncer::STOP_SYNC_FOR_DISABLED_ACCOUNT:
       // Sync disabled by domain admin. we should stop syncing until next
       // restart.
@@ -1407,17 +1262,6 @@ void ProfileSyncService::OnActionableError(const SyncProtocolError& error) {
       NOTREACHED();
   }
   NotifyObservers();
-
-  if (error.action == syncer::DISABLE_SYNC_ON_CLIENT ||
-      (error.action == syncer::DISABLE_SYNC_AND_ROLLBACK &&
-          !backup_rollback_controller_->StartRollback())) {
-    // Clean up backup data for sign-out only or when rollback is disabled.
-    CleanUpBackup();
-  } else if (error.action == syncer::ROLLBACK_DONE) {
-    // Shut down ROLLBACK backend and delete backup DB.
-    ShutdownImpl(syncer::DISABLE_SYNC);
-    sync_prefs_.ClearFirstSyncTime();
-  }
 }
 
 void ProfileSyncService::OnLocalSetPassphraseEncryption(
@@ -1437,7 +1281,6 @@ void ProfileSyncService::OnLocalSetPassphraseEncryption(
 }
 
 void ProfileSyncService::BeginConfigureCatchUpBeforeClear() {
-  DCHECK_EQ(backend_mode_, SYNC);
   DCHECK(data_type_manager_);
   DCHECK(!saved_nigori_state_);
   saved_nigori_state_ =
@@ -1472,26 +1315,6 @@ void ProfileSyncService::OnConfigureDone(
   configure_status_ = result.status;
   data_type_status_table_ = result.data_type_status_table;
 
-  if (backend_mode_ != SYNC) {
-    if (configure_status_ == DataTypeManager::OK) {
-      StartSyncingWithServer();
-
-      // Backup is done after models are associated.
-      if (backend_mode_ == BACKUP)
-        backup_finished_ = true;
-
-      // Asynchronously check whether sync needs to start.
-      base::ThreadTaskRunnerHandle::Get()->PostTask(
-          FROM_HERE, base::Bind(&ProfileSyncService::TryStartSyncAfterBackup,
-                                startup_controller_weak_factory_.GetWeakPtr()));
-    } else if (!expect_sync_configuration_aborted_) {
-      DVLOG(1) << "Backup/rollback backend failed to configure.";
-      ShutdownImpl(syncer::STOP_SYNC);
-    }
-
-    return;
-  }
-
   // We should have cleared our cached passphrase before we get here (in
   // OnBackendInitialized()).
   DCHECK(cached_passphrase_.empty());
@@ -1594,10 +1417,6 @@ ProfileSyncService::SyncStatusSummary
     return UNRECOVERABLE_ERROR;
   } else if (!backend_) {
     return NOT_ENABLED;
-  } else if (backend_mode_ == BACKUP) {
-    return BACKUP_USER_DATA;
-  } else if (backend_mode_ == ROLLBACK) {
-    return ROLLBACK_USER_DATA;
   } else if (backend_.get() && !IsFirstSetupComplete()) {
     return SETUP_INCOMPLETE;
   } else if (backend_ && IsFirstSetupComplete() && data_type_manager_ &&
@@ -1627,10 +1446,6 @@ std::string ProfileSyncService::QuerySyncStatusSummaryString() {
       return "Datatypes not fully initialized";
     case INITIALIZED:
       return "Sync service initialized";
-    case BACKUP_USER_DATA:
-      return "Backing-up user data. Status: " + config_status_str;
-    case ROLLBACK_USER_DATA:
-      return "Restoring user data. Status: " + config_status_str;
     default:
       return "Status unknown: Internal error?";
   }
@@ -1685,7 +1500,7 @@ bool ProfileSyncService::IsSyncAllowed() const {
 }
 
 bool ProfileSyncService::IsSyncActive() const {
-  return backend_initialized_ && backend_mode_ == SYNC && data_type_manager_ &&
+  return backend_initialized_ && data_type_manager_ &&
          data_type_manager_->state() != DataTypeManager::STOPPED;
 }
 
@@ -1703,10 +1518,6 @@ bool ProfileSyncService::IsBackendInitialized() const {
   return backend_initialized_;
 }
 
-ProfileSyncService::BackendMode ProfileSyncService::backend_mode() const {
-  return backend_mode_;
-}
-
 bool ProfileSyncService::ConfigurationDone() const {
   return data_type_manager_ &&
          data_type_manager_->state() == DataTypeManager::CONFIGURED;
@@ -1927,7 +1738,7 @@ void ProfileSyncService::ConfigureDataTypeManager() {
   // start syncing data until the user is done configuring encryption options,
   // etc. ReconfigureDatatypeManager() will get called again once the UI calls
   // SetSetupInProgress(false).
-  if (backend_mode_ == SYNC && startup_controller_->IsSetupInProgress())
+  if (startup_controller_->IsSetupInProgress())
     return;
 
   bool restart = false;
@@ -1947,24 +1758,19 @@ void ProfileSyncService::ConfigureDataTypeManager() {
 
   syncer::ModelTypeSet types;
   syncer::ConfigureReason reason = syncer::CONFIGURE_REASON_UNKNOWN;
-  if (backend_mode_ == BACKUP || backend_mode_ == ROLLBACK) {
-    types = syncer::BackupTypes();
-    reason = syncer::CONFIGURE_REASON_BACKUP_ROLLBACK;
+  types = GetPreferredDataTypes();
+  if (!IsFirstSetupComplete()) {
+    reason = syncer::CONFIGURE_REASON_NEW_CLIENT;
+  } else if (restart) {
+    // Datatype downloads on restart are generally due to newly supported
+    // datatypes (although it's also possible we're picking up where a failed
+    // previous configuration left off).
+    // TODO(sync): consider detecting configuration recovery and setting
+    // the reason here appropriately.
+    reason = syncer::CONFIGURE_REASON_NEWLY_ENABLED_DATA_TYPE;
   } else {
-    types = GetPreferredDataTypes();
-    if (!IsFirstSetupComplete()) {
-      reason = syncer::CONFIGURE_REASON_NEW_CLIENT;
-    } else if (restart) {
-      // Datatype downloads on restart are generally due to newly supported
-      // datatypes (although it's also possible we're picking up where a failed
-      // previous configuration left off).
-      // TODO(sync): consider detecting configuration recovery and setting
-      // the reason here appropriately.
-      reason = syncer::CONFIGURE_REASON_NEWLY_ENABLED_DATA_TYPE;
-    } else {
-      // The user initiated a reconfiguration (either to add or remove types).
-      reason = syncer::CONFIGURE_REASON_RECONFIGURATION;
-    }
+    // The user initiated a reconfiguration (either to add or remove types).
+    reason = syncer::CONFIGURE_REASON_RECONFIGURATION;
   }
 
   data_type_manager_->Configure(types, reason);
@@ -2266,11 +2072,6 @@ void ProfileSyncService::GoogleSignedOut(const std::string& account_id,
   UMA_HISTOGRAM_ENUMERATION("Sync.StopSource", syncer::SIGN_OUT,
                             syncer::STOP_SOURCE_LIMIT);
   RequestStop(CLEAR_DATA);
-
-  if (sync_driver::BackupRollbackController::IsBackupEnabled()) {
-    need_backup_ = true;
-    backup_finished_ = false;
-  }
 }
 
 void ProfileSyncService::AddObserver(
@@ -2534,21 +2335,6 @@ void ProfileSyncService::OnInternalUnrecoverableError(
   OnUnrecoverableErrorImpl(from_here, message, delete_sync_database);
 }
 
-syncer::SyncManagerFactory::MANAGER_TYPE
-ProfileSyncService::GetManagerType() const {
-  switch (backend_mode_) {
-    case SYNC:
-      return syncer::SyncManagerFactory::NORMAL;
-    case BACKUP:
-      return syncer::SyncManagerFactory::BACKUP;
-    case ROLLBACK:
-      return syncer::SyncManagerFactory::ROLLBACK;
-    case IDLE:
-      NOTREACHED();
-  }
-  return syncer::SyncManagerFactory::NORMAL;
-}
-
 bool ProfileSyncService::IsRetryingAccessTokenFetchForTest() const {
   return request_access_token_retry_timer_.IsRunning();
 }
@@ -2588,97 +2374,18 @@ void ProfileSyncService::OverrideNetworkResourcesForTest(
 }
 
 bool ProfileSyncService::HasSyncingBackend() const {
-  return backend_mode_ != SYNC ? false : backend_ != NULL;
+  return backend_ != NULL;
 }
 
 void ProfileSyncService::UpdateFirstSyncTimePref() {
   if (!IsSignedIn()) {
-    // Clear if user's not signed in and rollback is done.
-    if (backend_mode_ != ROLLBACK)
-      sync_prefs_.ClearFirstSyncTime();
-  } else if (sync_prefs_.GetFirstSyncTime().is_null() &&
-      backend_mode_ == SYNC) {
+    sync_prefs_.ClearFirstSyncTime();
+  } else if (sync_prefs_.GetFirstSyncTime().is_null()) {
     // Set if not set before and it's syncing now.
     sync_prefs_.SetFirstSyncTime(base::Time::Now());
   }
 }
 
-void ProfileSyncService::ClearBrowsingDataSinceFirstSync() {
-  base::Time first_sync_time = sync_prefs_.GetFirstSyncTime();
-  if (first_sync_time.is_null())
-    return;
-
-  sync_client_->GetClearBrowsingDataCallback().Run(first_sync_time,
-                                                   base::Time::Now());
-}
-
-void ProfileSyncService::CheckSyncBackupIfNeeded() {
-  DCHECK_EQ(backend_mode_, SYNC);
-
-#if BUILDFLAG(ENABLE_PRE_SYNC_BACKUP)
-  const base::Time last_synced_time = sync_prefs_.GetLastSyncedTime();
-  // Check backup once a day.
-  if (!last_backup_time_ &&
-      (last_synced_time.is_null() ||
-          base::Time::Now() - last_synced_time >=
-              base::TimeDelta::FromDays(1))) {
-    // If sync thread is set, need to serialize check on sync thread after
-    // closing backup DB.
-    if (sync_thread_) {
-      sync_thread_->task_runner()->PostTask(
-          FROM_HERE,
-          base::Bind(syncer::CheckSyncDbLastModifiedTime,
-                     base_directory_.Append(kSyncBackupDataFolderName),
-                     base::ThreadTaskRunnerHandle::Get(),
-                     base::Bind(&ProfileSyncService::CheckSyncBackupCallback,
-                                weak_factory_.GetWeakPtr())));
-    } else {
-      file_thread_->PostTask(
-          FROM_HERE,
-          base::Bind(syncer::CheckSyncDbLastModifiedTime,
-                     base_directory_.Append(kSyncBackupDataFolderName),
-                     base::ThreadTaskRunnerHandle::Get(),
-                     base::Bind(&ProfileSyncService::CheckSyncBackupCallback,
-                                weak_factory_.GetWeakPtr())));
-    }
-  }
-#endif
-}
-
-void ProfileSyncService::CheckSyncBackupCallback(base::Time backup_time) {
-  last_backup_time_.reset(new base::Time(backup_time));
-
-  DCHECK(device_info_sync_service_);
-  device_info_sync_service_->UpdateLocalDeviceBackupTime(*last_backup_time_);
-}
-
-void ProfileSyncService::TryStartSyncAfterBackup() {
-  startup_controller_->Reset(GetRegisteredDataTypes());
-  startup_controller_->TryStart();
-}
-
-void ProfileSyncService::CleanUpBackup() {
-  sync_prefs_.ClearFirstSyncTime();
-
-  // Use the client's base directory to get the blocking task runner to use in
-  // order to ensure ordering between the tasks posted by different invocations
-  // of this method.
-  scoped_refptr<base::SequencedTaskRunner> blocking_task_runner =
-      JsonPrefStore::GetTaskRunnerForFile(base_directory_, blocking_pool_);
-  blocking_task_runner->PostTask(
-      FROM_HERE,
-      base::Bind(base::IgnoreResult(base::DeleteFile),
-                 base_directory_.Append(kSyncBackupDataFolderName), true));
-}
-
-bool ProfileSyncService::NeedBackup() const {
-  return need_backup_;
-}
-
-base::Time ProfileSyncService::GetDeviceBackupTimeForTesting() const {
-  return device_info_sync_service_->GetLocalDeviceBackupTime();
-}
-
 void ProfileSyncService::FlushDirectory() const {
   // backend_initialized_ implies backend_ isn't NULL and the manager exists.
   // If sync is not initialized yet, we fail silently.
diff --git a/components/browser_sync/browser/profile_sync_service.h b/components/browser_sync/browser/profile_sync_service.h
index ada1731..df981bc 100644
--- a/components/browser_sync/browser/profile_sync_service.h
+++ b/components/browser_sync/browser/profile_sync_service.h
@@ -25,7 +25,6 @@
 #include "build/build_config.h"
 #include "components/keyed_service/core/keyed_service.h"
 #include "components/signin/core/browser/signin_manager_base.h"
-#include "components/sync_driver/backup_rollback_controller.h"
 #include "components/sync_driver/data_type_controller.h"
 #include "components/sync_driver/data_type_manager.h"
 #include "components/sync_driver/data_type_manager_observer.h"
@@ -219,18 +218,9 @@ class ProfileSyncService : public sync_driver::SyncService,
     SETUP_INCOMPLETE,
     DATATYPES_NOT_INITIALIZED,
     INITIALIZED,
-    BACKUP_USER_DATA,
-    ROLLBACK_USER_DATA,
     UNKNOWN_ERROR,
   };
 
-  enum BackendMode {
-    IDLE,       // No backend.
-    SYNC,       // Backend for syncing.
-    BACKUP,     // Backend for backup.
-    ROLLBACK    // Backend for rollback.
-  };
-
   // Bundles the arguments for ProfileSyncService construction. This is a
   // movable struct. Because of the non-POD data members, it needs out-of-line
   // constructors, so in particular the move constructor needs to be
@@ -567,11 +557,6 @@ class ProfileSyncService : public sync_driver::SyncService,
 
   virtual bool IsDataTypeControllerRunning(syncer::ModelType type) const;
 
-  // Returns the current mode the backend is in.
-  BackendMode backend_mode() const;
-
-  base::Time GetDeviceBackupTimeForTesting() const;
-
   // This triggers a Directory::SaveChanges() call on the sync thread.
   // It should be used to persist data to disk when the process might be
   // killed in the near future.
@@ -623,8 +608,6 @@ class ProfileSyncService : public sync_driver::SyncService,
       const std::string& message,
       bool delete_sync_database);
 
-  virtual bool NeedBackup() const;
-
   // This is a cache of the last authentication response we received from the
   // sync server. The UI queries this to display appropriate messaging to the
   // user.
@@ -733,9 +716,8 @@ class ProfileSyncService : public sync_driver::SyncService,
 
   void ClearUnrecoverableError();
 
-  // Starts up the backend sync components. |mode| specifies the kind of
-  // backend to start, one of SYNC, BACKUP or ROLLBACK.
-  virtual void StartUpSlowBackendComponents(BackendMode mode);
+  // Starts up the backend sync components.
+  virtual void StartUpSlowBackendComponents();
 
   // Collects preferred sync data types from |preference_providers_|.
   syncer::ModelTypeSet GetDataTypesFromPreferenceProviders() const;
@@ -759,9 +741,6 @@ class ProfileSyncService : public sync_driver::SyncService,
                                     bool delete_sync_database,
                                     UnrecoverableErrorReason reason);
 
-  // Returns the type of manager to use according to |backend_mode_|.
-  syncer::SyncManagerFactory::MANAGER_TYPE GetManagerType() const;
-
   // Update UMA for syncing backend.
   void UpdateBackendInitUMA(bool success);
 
@@ -777,22 +756,6 @@ class ProfileSyncService : public sync_driver::SyncService,
   // Update first sync time stored in preferences
   void UpdateFirstSyncTimePref();
 
-  // Clear browsing data since first sync during rollback.
-  void ClearBrowsingDataSinceFirstSync();
-
-  // Post background task to check sync backup DB state if needed.
-  void CheckSyncBackupIfNeeded();
-
-  // Callback to receive backup DB check result.
-  void CheckSyncBackupCallback(base::Time backup_time);
-
-  // Callback function to call |startup_controller_|.TryStart() after
-  // backup/rollback finishes;
-  void TryStartSyncAfterBackup();
-
-  // Clean up prefs and backup DB when rollback is not needed.
-  void CleanUpBackup();
-
   // Tell the sync server that this client has disabled sync.
   void RemoveClientFromServer() const;
 
@@ -987,23 +950,6 @@ class ProfileSyncService : public sync_driver::SyncService,
   browser_sync::ProfileSyncServiceStartBehavior start_behavior_;
   scoped_ptr<browser_sync::StartupController> startup_controller_;
 
-  scoped_ptr<sync_driver::BackupRollbackController> backup_rollback_controller_;
-
-  // Mode of current backend.
-  BackendMode backend_mode_;
-
-  // Whether backup is needed before sync starts.
-  bool need_backup_;
-
-  // Whether backup is finished.
-  bool backup_finished_;
-
-  base::Time backup_start_time_;
-
-  // Last time when pre-sync data was saved. NULL pointer means backup data
-  // state is unknown. If time value is null, backup data doesn't exist.
-  scoped_ptr<base::Time> last_backup_time_;
-
   // The full path to the sync data directory.
   base::FilePath directory_path_;
 
diff --git a/components/browser_sync/browser/profile_sync_service_mock.h b/components/browser_sync/browser/profile_sync_service_mock.h
index 41df3ea..255aa2f 100644
--- a/components/browser_sync/browser/profile_sync_service_mock.h
+++ b/components/browser_sync/browser/profile_sync_service_mock.h
@@ -96,8 +96,6 @@ class ProfileSyncServiceMock : public ProfileSyncService {
   MOCK_METHOD1(SetDecryptionPassphrase, bool(const std::string& passphrase));
   MOCK_METHOD2(SetEncryptionPassphrase, void(const std::string& passphrase,
                                              PassphraseType type));
-
-  MOCK_METHOD1(StartUpSlowBackendComponents, void(BackendMode));
 };
 
 #endif  // COMPONENTS_BROWSER_SYNC_BROWSER_PROFILE_SYNC_SERVICE_MOCK_H_
diff --git a/components/browser_sync/browser/profile_sync_service_startup_unittest.cc b/components/browser_sync/browser/profile_sync_service_startup_unittest.cc
index 122fb32..206ce89 100644
--- a/components/browser_sync/browser/profile_sync_service_startup_unittest.cc
+++ b/components/browser_sync/browser/profile_sync_service_startup_unittest.cc
@@ -74,16 +74,6 @@ ACTION_P3(InvokeOnConfigureDone, sync_service, error_callback, result) {
   sync_service->OnConfigureDone(configure_result);
 }
 
-class TestProfileSyncServiceNoBackup : public ProfileSyncService {
- public:
-  explicit TestProfileSyncServiceNoBackup(
-      ProfileSyncService::InitParams init_params)
-      : ProfileSyncService(std::move(init_params)) {}
-
- protected:
-  bool NeedBackup() const override { return false; }
-};
-
 class ProfileSyncServiceStartupTest : public testing::Test {
  public:
   ProfileSyncServiceStartupTest() {
@@ -105,8 +95,7 @@ class ProfileSyncServiceStartupTest : public testing::Test {
         profile_sync_service_bundle_.CreateBasicInitParams(start_behavior,
                                                            builder.Build());
 
-    sync_service_.reset(
-        new TestProfileSyncServiceNoBackup(std::move(init_params)));
+    sync_service_.reset(new ProfileSyncService(std::move(init_params)));
     sync_service_->RegisterDataTypeController(
         new sync_driver::FakeDataTypeController(syncer::BOOKMARKS));
     sync_service_->AddObserver(&observer_);
diff --git a/components/browser_sync/browser/profile_sync_service_unittest.cc b/components/browser_sync/browser/profile_sync_service_unittest.cc
index 69df103..b348ffa 100644
--- a/components/browser_sync/browser/profile_sync_service_unittest.cc
+++ b/components/browser_sync/browser/profile_sync_service_unittest.cc
@@ -32,7 +32,6 @@
 #include "components/sync_driver/glue/sync_backend_host_mock.h"
 #include "components/sync_driver/pref_names.h"
 #include "components/sync_driver/sync_api_component_factory_mock.h"
-#include "components/sync_driver/sync_driver_features.h"
 #include "components/sync_driver/sync_driver_switches.h"
 #include "components/sync_driver/sync_prefs.h"
 #include "components/sync_driver/sync_service_observer.h"
@@ -240,9 +239,6 @@ class ProfileSyncServiceTest : public ::testing::Test {
     component_factory_ = profile_sync_service_bundle_.component_factory();
     ProfileSyncServiceBundle::SyncClientBuilder builder(
         &profile_sync_service_bundle_);
-    builder.SetClearBrowsingDataCallback(
-        base::Bind(&ProfileSyncServiceTest::ClearBrowsingDataCallback,
-                   base::Unretained(this)));
     ProfileSyncService::InitParams init_params =
         profile_sync_service_bundle_.CreateBasicInitParams(behavior,
                                                            builder.Build());
@@ -268,8 +264,7 @@ class ProfileSyncServiceTest : public ::testing::Test {
   }
 
   void InitializeForNthSync() {
-    // Set first sync time before initialize to disable backup and simulate
-    // a complete sync setup.
+    // Set first sync time before initialize to simulate a complete sync setup.
     sync_driver::SyncPrefs sync_prefs(
         service_->GetSyncClient()->GetPrefService());
     sync_prefs.SetFirstSyncTime(base::Time::Now());
@@ -378,10 +373,6 @@ class ProfileSyncServiceTest : public ::testing::Test {
     return component_factory_;
   }
 
-  void ClearBrowsingDataCallback(base::Time start, base::Time end) {
-    clear_browsing_date_start_ = start;
-  }
-
  protected:
   void PumpLoop() {
     base::RunLoop run_loop;
@@ -390,9 +381,6 @@ class ProfileSyncServiceTest : public ::testing::Test {
     run_loop.Run();
   }
 
-  // The requested start time when ClearBrowsingDataCallback is called.
-  base::Time clear_browsing_date_start_;
-
  private:
   base::MessageLoop message_loop_;
   browser_sync::ProfileSyncServiceBundle profile_sync_service_bundle_;
@@ -423,7 +411,6 @@ TEST_F(ProfileSyncServiceTest, SuccessfulInitialization) {
   InitializeForNthSync();
   EXPECT_FALSE(service()->IsManaged());
   EXPECT_TRUE(service()->IsSyncActive());
-  EXPECT_EQ(ProfileSyncService::SYNC, service()->backend_mode());
 }
 
 // Verify that the SetSetupInProgress function call updates state
@@ -639,107 +626,6 @@ TEST_F(ProfileSyncServiceTest, SignOutRevokeAccessToken) {
 }
 #endif
 
-#if BUILDFLAG(ENABLE_PRE_SYNC_BACKUP)
-TEST_F(ProfileSyncServiceTest, DontStartBackupOnBrowserStart) {
-  CreateServiceWithoutSignIn();
-  InitializeForFirstSync();
-  PumpLoop();
-  EXPECT_EQ(ProfileSyncService::IDLE, service()->backend_mode());
-}
-
-TEST_F(ProfileSyncServiceTest, BackupBeforeFirstSync) {
-  CreateServiceWithoutSignIn();
-  ExpectDataTypeManagerCreation(2, GetDefaultConfigureCalledCallback());
-  std::vector<bool> delete_dir_param;
-  ExpectSyncBackendHostCreationCollectDeleteDir(2, &delete_dir_param);
-  InitializeForFirstSync();
-
-  signin_manager()->SetAuthenticatedAccountInfo(kGaiaId, kEmail);
-  IssueTestTokens();
-  PumpLoop();
-
-  // At this time, backup is finished. Task is posted to start sync again.
-  EXPECT_EQ(ProfileSyncService::BACKUP, service()->backend_mode());
-  EXPECT_FALSE(service()->IsSyncActive());
-  EXPECT_EQ(1u, delete_dir_param.size());
-  EXPECT_TRUE(delete_dir_param[0]);
-
-  // Pump loop to start sync.
-  PumpLoop();
-  EXPECT_EQ(ProfileSyncService::SYNC, service()->backend_mode());
-  EXPECT_TRUE(service()->IsSyncActive());
-  EXPECT_EQ(2u, delete_dir_param.size());
-  EXPECT_TRUE(delete_dir_param[0]);
-}
-
-// Test backup is done again on browser start if user signed in last session
-// but backup didn't finish when last session was closed.
-TEST_F(ProfileSyncServiceTest, ResumeBackupIfAborted) {
-  IssueTestTokens();
-  CreateService(AUTO_START);
-  ExpectDataTypeManagerCreation(2, GetDefaultConfigureCalledCallback());
-  std::vector<bool> delete_dir_param;
-  ExpectSyncBackendHostCreationCollectDeleteDir(2, &delete_dir_param);
-  InitializeForFirstSync();
-  PumpLoop();
-
-  // At this time, backup is finished. Task is posted to start sync again.
-  EXPECT_EQ(ProfileSyncService::BACKUP, service()->backend_mode());
-  EXPECT_FALSE(service()->IsSyncActive());
-  EXPECT_EQ(1u, delete_dir_param.size());
-  EXPECT_TRUE(delete_dir_param[0]);
-
-  // Pump loop to start sync.
-  PumpLoop();
-  EXPECT_EQ(ProfileSyncService::SYNC, service()->backend_mode());
-  EXPECT_TRUE(service()->IsSyncActive());
-  EXPECT_EQ(2u, delete_dir_param.size());
-  EXPECT_TRUE(delete_dir_param[0]);
-}
-
-TEST_F(ProfileSyncServiceTest, Rollback) {
-  CreateService(browser_sync::MANUAL_START);
-  service()->SetFirstSetupComplete();
-  ExpectDataTypeManagerCreation(2, GetDefaultConfigureCalledCallback());
-  std::vector<bool> delete_dir_param;
-  ExpectSyncBackendHostCreationCollectDeleteDir(2, &delete_dir_param);
-  IssueTestTokens();
-  InitializeForNthSync();
-  EXPECT_TRUE(service()->IsSyncActive());
-  EXPECT_EQ(ProfileSyncService::SYNC, service()->backend_mode());
-
-  // First sync time should be recorded.
-  sync_driver::SyncPrefs sync_prefs(
-      service()->GetSyncClient()->GetPrefService());
-  base::Time first_sync_time = sync_prefs.GetFirstSyncTime();
-  EXPECT_FALSE(first_sync_time.is_null());
-
-  syncer::SyncProtocolError client_cmd;
-  client_cmd.action = syncer::DISABLE_SYNC_AND_ROLLBACK;
-  service()->OnActionableError(client_cmd);
-  EXPECT_EQ(ProfileSyncService::IDLE, service()->backend_mode());
-
-  // Pump loop to run rollback.
-  PumpLoop();
-  EXPECT_EQ(ProfileSyncService::ROLLBACK, service()->backend_mode());
-
-  // Browser data should be cleared during rollback.
-  EXPECT_EQ(first_sync_time, clear_browsing_date_start_);
-
-  client_cmd.action = syncer::ROLLBACK_DONE;
-  service()->OnActionableError(client_cmd);
-  EXPECT_EQ(ProfileSyncService::IDLE, service()->backend_mode());
-
-  // First sync time is erased after rollback is done.
-  EXPECT_TRUE(sync_prefs.GetFirstSyncTime().is_null());
-
-  EXPECT_EQ(2u, delete_dir_param.size());
-  EXPECT_FALSE(delete_dir_param[0]);
-  EXPECT_FALSE(delete_dir_param[1]);
-}
-
-#endif  // ENABLE_PRE_SYNC_BACKUP
-
 // Verify that LastSyncedTime is cleared when the user signs out.
 TEST_F(ProfileSyncServiceTest, ClearLastSyncedTimeOnSignOut) {
   IssueTestTokens();
@@ -834,7 +720,6 @@ TEST_F(ProfileSyncServiceTest, OnLocalSetPassphraseEncryption) {
       1, GetRecordingConfigureCalledCallback(&configure_reason));
   InitializeForNthSync();
   EXPECT_TRUE(service()->IsSyncActive());
-  EXPECT_EQ(ProfileSyncService::SYNC, service()->backend_mode());
   testing::Mock::VerifyAndClearExpectations(component_factory());
   EXPECT_EQ(syncer::CONFIGURE_REASON_NEWLY_ENABLED_DATA_TYPE, configure_reason);
   sync_driver::DataTypeManager::ConfigureResult result;
@@ -878,7 +763,6 @@ TEST_F(ProfileSyncServiceTest,
   ExpectDataTypeManagerCreation(
       1, GetRecordingConfigureCalledCallback(&configure_reason));
   InitializeForNthSync();
-  EXPECT_EQ(ProfileSyncService::SYNC, service()->backend_mode());
   testing::Mock::VerifyAndClearExpectations(component_factory());
   EXPECT_EQ(syncer::CONFIGURE_REASON_NEWLY_ENABLED_DATA_TYPE, configure_reason);
   sync_driver::DataTypeManager::ConfigureResult result;
@@ -933,7 +817,6 @@ TEST_F(ProfileSyncServiceTest,
   ExpectSyncBackendHostCreationCaptureClearServerData(&captured_callback);
   ExpectDataTypeManagerCreation(1, GetDefaultConfigureCalledCallback());
   InitializeForNthSync();
-  EXPECT_EQ(ProfileSyncService::SYNC, service()->backend_mode());
   testing::Mock::VerifyAndClearExpectations(component_factory());
 
   // Simulate user entering encryption passphrase.
@@ -1018,7 +901,6 @@ TEST_F(ProfileSyncServiceTest, ResetSyncData) {
   syncer::SyncProtocolError client_cmd;
   client_cmd.action = syncer::RESET_LOCAL_SYNC_DATA;
   service()->OnActionableError(client_cmd);
-  EXPECT_EQ(ProfileSyncService::SYNC, service()->backend_mode());
 }
 
 // Regression test for crbug/555434. The issue is that check for sessions DTC in
diff --git a/components/browser_sync/browser/profile_sync_test_util.cc b/components/browser_sync/browser/profile_sync_test_util.cc
index c0c678f..1f1ecd8 100644
--- a/components/browser_sync/browser/profile_sync_test_util.cc
+++ b/components/browser_sync/browser/profile_sync_test_util.cc
@@ -15,8 +15,6 @@
 #include "net/url_request/url_request_test_util.h"
 #include "sync/internal_api/public/engine/passive_model_worker.h"
 
-using sync_driver::ClearBrowsingDataCallback;
-
 namespace browser_sync {
 
 namespace {
@@ -26,7 +24,6 @@ class BundleSyncClient : public sync_driver::FakeSyncClient {
   BundleSyncClient(
       sync_driver::SyncApiComponentFactory* factory,
       PrefService* pref_service,
-      const ClearBrowsingDataCallback& clear_browsing_data_callback,
       sync_sessions::SyncSessionsClient* sync_sessions_client,
       autofill::PersonalDataManager* personal_data_manager,
       const base::Callback<base::WeakPtr<syncer::SyncableService>(
@@ -42,7 +39,6 @@ class BundleSyncClient : public sync_driver::FakeSyncClient {
   ~BundleSyncClient() override;
 
   PrefService* GetPrefService() override;
-  ClearBrowsingDataCallback GetClearBrowsingDataCallback() override;
   sync_sessions::SyncSessionsClient* GetSyncSessionsClient() override;
   autofill::PersonalDataManager* GetPersonalDataManager() override;
   base::WeakPtr<syncer::SyncableService> GetSyncableServiceForType(
@@ -56,7 +52,6 @@ class BundleSyncClient : public sync_driver::FakeSyncClient {
 
  private:
   PrefService* const pref_service_;
-  const ClearBrowsingDataCallback clear_browsing_data_callback_;
   sync_sessions::SyncSessionsClient* const sync_sessions_client_;
   autofill::PersonalDataManager* const personal_data_manager_;
   const base::Callback<base::WeakPtr<syncer::SyncableService>(
@@ -75,7 +70,6 @@ class BundleSyncClient : public sync_driver::FakeSyncClient {
 BundleSyncClient::BundleSyncClient(
     sync_driver::SyncApiComponentFactory* factory,
     PrefService* pref_service,
-    const ClearBrowsingDataCallback& clear_browsing_data_callback,
     sync_sessions::SyncSessionsClient* sync_sessions_client,
     autofill::PersonalDataManager* personal_data_manager,
     const base::Callback<base::WeakPtr<syncer::SyncableService>(
@@ -89,7 +83,6 @@ BundleSyncClient::BundleSyncClient(
     history::HistoryService* history_service)
     : sync_driver::FakeSyncClient(factory),
       pref_service_(pref_service),
-      clear_browsing_data_callback_(clear_browsing_data_callback),
       sync_sessions_client_(sync_sessions_client),
       personal_data_manager_(personal_data_manager),
       get_syncable_service_callback_(get_syncable_service_callback),
@@ -107,10 +100,6 @@ PrefService* BundleSyncClient::GetPrefService() {
   return pref_service_;
 }
 
-ClearBrowsingDataCallback BundleSyncClient::GetClearBrowsingDataCallback() {
-  return clear_browsing_data_callback_;
-}
-
 sync_sessions::SyncSessionsClient* BundleSyncClient::GetSyncSessionsClient() {
   return sync_sessions_client_;
 }
@@ -195,11 +184,6 @@ ProfileSyncServiceBundle::SyncClientBuilder::SyncClientBuilder(
     ProfileSyncServiceBundle* bundle)
     : bundle_(bundle) {}
 
-void ProfileSyncServiceBundle::SyncClientBuilder::SetClearBrowsingDataCallback(
-    ClearBrowsingDataCallback clear_browsing_data_callback) {
-  clear_browsing_data_callback_ = clear_browsing_data_callback;
-}
-
 void ProfileSyncServiceBundle::SyncClientBuilder::SetPersonalDataManager(
     autofill::PersonalDataManager* personal_data_manager) {
   personal_data_manager_ = personal_data_manager;
@@ -234,9 +218,9 @@ scoped_ptr<sync_driver::FakeSyncClient>
 ProfileSyncServiceBundle::SyncClientBuilder::Build() {
   return make_scoped_ptr(new BundleSyncClient(
       bundle_->component_factory(), bundle_->pref_service(),
-      clear_browsing_data_callback_, bundle_->sync_sessions_client(),
-      personal_data_manager_, get_syncable_service_callback_,
-      get_sync_service_callback_, get_bookmark_model_callback_,
+      bundle_->sync_sessions_client(), personal_data_manager_,
+      get_syncable_service_callback_, get_sync_service_callback_,
+      get_bookmark_model_callback_,
       activate_model_creation_ ? bundle_->db_thread() : nullptr,
       activate_model_creation_ ? base::ThreadTaskRunnerHandle::Get() : nullptr,
       history_service_));
diff --git a/components/browser_sync/browser/profile_sync_test_util.h b/components/browser_sync/browser/profile_sync_test_util.h
index b5bea3a..0953ffb 100644
--- a/components/browser_sync/browser/profile_sync_test_util.h
+++ b/components/browser_sync/browser/profile_sync_test_util.h
@@ -79,10 +79,6 @@ class ProfileSyncServiceBundle {
 
     ~SyncClientBuilder();
 
-    // Setters for the various additional data for the client to return.
-    void SetClearBrowsingDataCallback(
-        sync_driver::ClearBrowsingDataCallback clear_browsing_data_callback);
-
     void SetPersonalDataManager(
         autofill::PersonalDataManager* personal_data_manager);
 
@@ -111,7 +107,6 @@ class ProfileSyncServiceBundle {
     // Associated bundle to source objects from.
     ProfileSyncServiceBundle* const bundle_;
 
-    sync_driver::ClearBrowsingDataCallback clear_browsing_data_callback_;
     autofill::PersonalDataManager* personal_data_manager_;
     base::Callback<base::WeakPtr<syncer::SyncableService>(
         syncer::ModelType type)>
diff --git a/components/browser_sync/browser/test_profile_sync_service.cc b/components/browser_sync/browser/test_profile_sync_service.cc
index 092fdfe..48ede52 100644
--- a/components/browser_sync/browser/test_profile_sync_service.cc
+++ b/components/browser_sync/browser/test_profile_sync_service.cc
@@ -30,7 +30,3 @@ void TestProfileSyncService::OnConfigureDone(
 syncer::UserShare* TestProfileSyncService::GetUserShare() const {
   return backend_->GetUserShare();
 }
-
-bool TestProfileSyncService::NeedBackup() const {
-  return false;
-}
diff --git a/components/browser_sync/browser/test_profile_sync_service.h b/components/browser_sync/browser/test_profile_sync_service.h
index 54b0c37..abd82aa 100644
--- a/components/browser_sync/browser/test_profile_sync_service.h
+++ b/components/browser_sync/browser/test_profile_sync_service.h
@@ -41,8 +41,6 @@ class TestProfileSyncService : public ProfileSyncService {
   // and cause memory leak in test.
   syncer::WeakHandle<syncer::JsEventHandler> GetJsEventHandler() override;
 
-  bool NeedBackup() const override;
-
  private:
   syncer::TestIdFactory id_factory_;
 
diff --git a/components/components_tests.gyp b/components/components_tests.gyp
index 0a0e078..46f7e81 100644
--- a/components/components_tests.gyp
+++ b/components/components_tests.gyp
@@ -742,7 +742,6 @@
     'sync_driver_unittest_sources': [
       'sync_driver/about_sync_util_unittest.cc',
       'sync_driver/backend_migrator_unittest.cc',
-      'sync_driver/backup_rollback_controller_unittest.cc',
       'sync_driver/data_type_manager_impl_unittest.cc',
       'sync_driver/device_info_data_type_controller_unittest.cc',
       'sync_driver/device_info_service_unittest.cc',
@@ -1115,7 +1114,6 @@
         'components.gyp:suggestions',
         'components.gyp:sync_bookmarks',
         'components.gyp:sync_driver',
-        'components.gyp:sync_driver_features',
         'components.gyp:sync_driver_test_support',
         'components.gyp:sync_sessions',
         'components.gyp:sync_sessions_test_support',
diff --git a/components/sync_driver.gypi b/components/sync_driver.gypi
index 0a4310b9a..ab98660 100644
--- a/components/sync_driver.gypi
+++ b/components/sync_driver.gypi
@@ -18,7 +18,6 @@
         'invalidation_public',
         'os_crypt',
         'signin_core_browser',
-        'sync_driver_features',
         'version_info',
       ],
       'export_dependent_settings': [
@@ -35,8 +34,6 @@
         'sync_driver/backend_data_type_configurer.h',
         'sync_driver/backend_migrator.cc',
         'sync_driver/backend_migrator.h',
-        'sync_driver/backup_rollback_controller.cc',
-        'sync_driver/backup_rollback_controller.h',
         'sync_driver/change_processor.cc',
         'sync_driver/change_processor.h',
         'sync_driver/data_type_controller.cc',
@@ -156,26 +153,6 @@
       ],
     },
     {
-      # GN version: //components/sync_driver:features
-      'target_name': 'sync_driver_features',
-      'includes': [ '../build/buildflag_header.gypi' ],
-      'variables': {
-        'buildflag_header_path': 'components/sync_driver/sync_driver_features.h',
-        'variables': {
-          'conditions': [
-            ['OS=="win" or OS=="mac" or (OS=="linux" and chromeos==0)', {
-              'enable_pre_sync_backup%': 1,
-            }, {
-              'enable_pre_sync_backup%': 0,
-            }],
-          ],
-        },
-        'buildflag_flags': [
-          "ENABLE_PRE_SYNC_BACKUP=<(enable_pre_sync_backup)",
-        ],
-      },
-    },
-    {
       'target_name': 'sync_driver_test_support',
       'type': 'static_library',
       'dependencies': [
diff --git a/components/sync_driver/BUILD.gn b/components/sync_driver/BUILD.gn
index b20c8bc..9ea51d5 100644
--- a/components/sync_driver/BUILD.gn
+++ b/components/sync_driver/BUILD.gn
@@ -13,8 +13,6 @@ source_set("sync_driver") {
     "backend_data_type_configurer.h",
     "backend_migrator.cc",
     "backend_migrator.h",
-    "backup_rollback_controller.cc",
-    "backup_rollback_controller.h",
     "change_processor.cc",
     "change_processor.h",
     "data_type_controller.cc",
@@ -122,7 +120,6 @@ source_set("sync_driver") {
   ]
 
   public_deps = [
-    ":features",
     "//third_party/cacheinvalidation",
   ]
   deps = [
@@ -205,7 +202,6 @@ source_set("unit_tests") {
   sources = [
     "about_sync_util_unittest.cc",
     "backend_migrator_unittest.cc",
-    "backup_rollback_controller_unittest.cc",
     "data_type_manager_impl_unittest.cc",
     "device_info_data_type_controller_unittest.cc",
     "device_info_service_unittest.cc",
@@ -257,12 +253,3 @@ source_set("unit_tests") {
     ]
   }
 }
-
-buildflag_header("features") {
-  header = "sync_driver_features.h"
-
-  # Whether to back up data before sync.
-  enable_pre_sync_backup = is_win || is_mac || (is_linux && !is_chromeos)
-
-  flags = [ "ENABLE_PRE_SYNC_BACKUP=$enable_pre_sync_backup" ]
-}
diff --git a/components/sync_driver/backup_rollback_controller.cc b/components/sync_driver/backup_rollback_controller.cc
deleted file mode 100644
index 3629973..0000000
--- a/components/sync_driver/backup_rollback_controller.cc
+++ /dev/null
@@ -1,103 +0,0 @@
-// Copyright 2014 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "components/sync_driver/backup_rollback_controller.h"
-
-#include <string>
-
-#include "base/command_line.h"
-#include "base/location.h"
-#include "base/metrics/field_trial.h"
-#include "base/single_thread_task_runner.h"
-#include "base/thread_task_runner_handle.h"
-#include "components/sync_driver/signin_manager_wrapper.h"
-#include "components/sync_driver/sync_driver_features.h"
-#include "components/sync_driver/sync_driver_switches.h"
-#include "components/sync_driver/sync_prefs.h"
-
-namespace sync_driver {
-
-#if BUILDFLAG(ENABLE_PRE_SYNC_BACKUP)
-// Number of rollback attempts to try before giving up.
-static const int kRollbackLimits = 3;
-
-// Finch experiment name and group.
-static char kSyncBackupFinchName[] = "SyncBackup";
-static char kSyncBackupFinchDisabled[] = "disabled";
-#endif
-
-BackupRollbackController::BackupRollbackController(
-    sync_driver::SyncPrefs* sync_prefs,
-    const SigninManagerWrapper* signin,
-    base::Closure start_backup,
-    base::Closure start_rollback)
-    : sync_prefs_(sync_prefs),
-      signin_(signin),
-      start_backup_(start_backup),
-      start_rollback_(start_rollback) {}
-
-BackupRollbackController::~BackupRollbackController() {}
-
-bool BackupRollbackController::StartBackup() {
-  if (!IsBackupEnabled())
-    return false;
-
-  // Disable rollback to previous backup DB because it will be overwritten by
-  // new backup.
-  sync_prefs_->SetRemainingRollbackTries(0);
-  base::ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE, start_backup_);
-  return true;
-}
-
-bool BackupRollbackController::StartRollback() {
-  if (!IsBackupEnabled())
-    return false;
-
-  // Don't roll back if disabled or user is signed in.
-  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
-          switches::kSyncDisableRollback) ||
-      !signin_->GetEffectiveUsername().empty()) {
-    sync_prefs_->SetRemainingRollbackTries(0);
-    return false;
-  }
-
-  int rollback_tries = sync_prefs_->GetRemainingRollbackTries();
-  if (rollback_tries <= 0)
-    return false;  // No pending rollback.
-
-  sync_prefs_->SetRemainingRollbackTries(rollback_tries - 1);
-  base::ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE, start_rollback_);
-  return true;
-}
-
-void BackupRollbackController::OnRollbackReceived() {
-#if BUILDFLAG(ENABLE_PRE_SYNC_BACKUP)
-  sync_prefs_->SetRemainingRollbackTries(kRollbackLimits);
-#endif
-}
-
-void BackupRollbackController::OnRollbackDone() {
-#if BUILDFLAG(ENABLE_PRE_SYNC_BACKUP)
-  sync_prefs_->SetRemainingRollbackTries(0);
-#endif
-}
-
-// static
-bool BackupRollbackController::IsBackupEnabled() {
-#if BUILDFLAG(ENABLE_PRE_SYNC_BACKUP)
-  const std::string group_name =
-      base::FieldTrialList::FindFullName(kSyncBackupFinchName);
-
-  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
-          switches::kSyncDisableBackup) ||
-      group_name == kSyncBackupFinchDisabled) {
-    return false;
-  }
-  return true;
-#else
-  return false;
-#endif
-}
-
-}  // namespace sync_driver
diff --git a/components/sync_driver/backup_rollback_controller.h b/components/sync_driver/backup_rollback_controller.h
deleted file mode 100644
index f8b6b26..0000000
--- a/components/sync_driver/backup_rollback_controller.h
+++ /dev/null
@@ -1,62 +0,0 @@
-// Copyright 2014 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef COMPONENTS_SYNC_DRIVER_BACKUP_ROLLBACK_CONTROLLER_H_
-#define COMPONENTS_SYNC_DRIVER_BACKUP_ROLLBACK_CONTROLLER_H_
-
-#include "base/callback.h"
-#include "base/macros.h"
-#include "base/memory/weak_ptr.h"
-
-class SigninManagerWrapper;
-
-namespace sync_driver {
-
-class SyncPrefs;
-
-// BackupRollbackController takes two closures for starting backup/rollback
-// process. It calls the closures according to user's signin status or
-// received rollback command. Backup is not run when user signed in, even when
-// sync is not running.
-class BackupRollbackController {
- public:
-  BackupRollbackController(sync_driver::SyncPrefs* sync_prefs,
-                           const SigninManagerWrapper* signin,
-                           base::Closure start_backup,
-                           base::Closure start_rollback);
-  ~BackupRollbackController();
-
-  // Post task to run |start_backup_| if conditions are met. Return true if
-  // task is posted, false otherwise.
-  bool StartBackup();
-
-  // Post task to run |start_rollback_| if conditions are met. Return true if
-  // task is posted, false otherwise.
-  bool StartRollback();
-
-  // Update rollback preference to indicate rollback is needed.
-  void OnRollbackReceived();
-
-  // Update rollback preference to indicate rollback is finished.
-  void OnRollbackDone();
-
-  // Return true if platform supports backup and backup is enabled.
-  static bool IsBackupEnabled();
-
- private:
-  sync_driver::SyncPrefs* sync_prefs_;
-
-  // Use SigninManagerWrapper instead of SigninManagerBase so that
-  // supervised users are treated like regular signed-in users.
-  const SigninManagerWrapper* signin_;
-
-  base::Closure start_backup_;
-  base::Closure start_rollback_;
-
-  DISALLOW_COPY_AND_ASSIGN(BackupRollbackController);
-};
-
-}  // namespace sync_driver
-
-#endif  // COMPONENTS_SYNC_DRIVER_BACKUP_ROLLBACK_CONTROLLER_H_
diff --git a/components/sync_driver/backup_rollback_controller_unittest.cc b/components/sync_driver/backup_rollback_controller_unittest.cc
deleted file mode 100644
index 7d5f9b6..0000000
--- a/components/sync_driver/backup_rollback_controller_unittest.cc
+++ /dev/null
@@ -1,148 +0,0 @@
-// Copyright 2014 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "components/sync_driver/backup_rollback_controller.h"
-
-#include <string>
-
-#include "base/command_line.h"
-#include "base/location.h"
-#include "base/memory/scoped_ptr.h"
-#include "base/run_loop.h"
-#include "base/single_thread_task_runner.h"
-#include "components/sync_driver/signin_manager_wrapper.h"
-#include "components/sync_driver/sync_driver_features.h"
-#include "components/sync_driver/sync_driver_switches.h"
-#include "components/sync_driver/sync_prefs.h"
-#include "testing/gmock/include/gmock/gmock.h"
-#include "testing/gtest/include/gtest/gtest.h"
-
-using ::testing::Return;
-
-namespace {
-
-#if BUILDFLAG(ENABLE_PRE_SYNC_BACKUP)
-
-class MockSigninManagerWrapper : public SigninManagerWrapper {
- public:
-  MockSigninManagerWrapper() : SigninManagerWrapper(NULL) {}
-
-  MOCK_CONST_METHOD0(GetEffectiveUsername, std::string());
-};
-
-class FakeSyncPrefs : public sync_driver::SyncPrefs {
- public:
-  FakeSyncPrefs() : rollback_tries_left_(0) {}
-
-  int GetRemainingRollbackTries() const override {
-    return rollback_tries_left_;
-  }
-
-  void SetRemainingRollbackTries(int v) override { rollback_tries_left_ = v; }
-
- private:
-  int rollback_tries_left_;
-};
-
-class BackupRollbackControllerTest : public testing::Test {
- public:
-  void ControllerCallback(bool start_backup) {
-    if (start_backup)
-      backup_started_ = true;
-    else
-      rollback_started_ = true;
-  }
-
- protected:
-  void SetUp() override {
-    backup_started_ = false;
-    rollback_started_ = false;
-
-    EXPECT_CALL(signin_wrapper_, GetEffectiveUsername())
-        .WillRepeatedly(Return(""));
-
-    controller_.reset(new sync_driver::BackupRollbackController(
-        &fake_prefs_, &signin_wrapper_,
-        base::Bind(&BackupRollbackControllerTest::ControllerCallback,
-                   base::Unretained(this), true),
-        base::Bind(&BackupRollbackControllerTest::ControllerCallback,
-                   base::Unretained(this), false)));
-  }
-
-  void PumpLoop() {
-    base::RunLoop run_loop;
-    loop_.task_runner()->PostTask(FROM_HERE, run_loop.QuitClosure());
-    run_loop.Run();
-  }
-
-  MockSigninManagerWrapper signin_wrapper_;
-  FakeSyncPrefs fake_prefs_;
-  scoped_ptr<sync_driver::BackupRollbackController> controller_;
-  bool backup_started_;
-  bool rollback_started_;
-  base::MessageLoop loop_;
-};
-
-TEST_F(BackupRollbackControllerTest, StartBackup) {
-  EXPECT_TRUE(controller_->StartBackup());
-  PumpLoop();
-  EXPECT_TRUE(backup_started_);
-}
-
-TEST_F(BackupRollbackControllerTest, NoBackupIfDisabled) {
-  base::CommandLine::ForCurrentProcess()->AppendSwitch(
-      switches::kSyncDisableBackup);
-
-  base::RunLoop run_loop;
-  EXPECT_FALSE(controller_->StartBackup());
-  loop_.task_runner()->PostTask(FROM_HERE, run_loop.QuitClosure());
-  run_loop.Run();
-  EXPECT_FALSE(backup_started_);
-}
-
-TEST_F(BackupRollbackControllerTest, StartRollback) {
-  fake_prefs_.SetRemainingRollbackTries(1);
-
-  EXPECT_TRUE(controller_->StartRollback());
-  PumpLoop();
-  EXPECT_TRUE(rollback_started_);
-  EXPECT_EQ(0, fake_prefs_.GetRemainingRollbackTries());
-}
-
-TEST_F(BackupRollbackControllerTest, NoRollbackIfOutOfTries) {
-  fake_prefs_.SetRemainingRollbackTries(0);
-
-  EXPECT_FALSE(controller_->StartRollback());
-  PumpLoop();
-  EXPECT_FALSE(rollback_started_);
-}
-
-TEST_F(BackupRollbackControllerTest, NoRollbackIfUserSignedIn) {
-  fake_prefs_.SetRemainingRollbackTries(1);
-  EXPECT_CALL(signin_wrapper_, GetEffectiveUsername())
-      .Times(1)
-      .WillOnce(Return("test"));
-  EXPECT_FALSE(controller_->StartRollback());
-  EXPECT_EQ(0, fake_prefs_.GetRemainingRollbackTries());
-
-  PumpLoop();
-  EXPECT_FALSE(backup_started_);
-  EXPECT_FALSE(rollback_started_);
-}
-
-TEST_F(BackupRollbackControllerTest, NoRollbackIfDisabled) {
-  fake_prefs_.SetRemainingRollbackTries(1);
-
-  base::CommandLine::ForCurrentProcess()->AppendSwitch(
-      switches::kSyncDisableRollback);
-  EXPECT_FALSE(controller_->StartRollback());
-  EXPECT_EQ(0, fake_prefs_.GetRemainingRollbackTries());
-
-  PumpLoop();
-  EXPECT_FALSE(rollback_started_);
-}
-
-#endif
-
-}  // anonymous namespace
diff --git a/components/sync_driver/data_type_manager_impl.cc b/components/sync_driver/data_type_manager_impl.cc
index 4450bec..b739611 100644
--- a/components/sync_driver/data_type_manager_impl.cc
+++ b/components/sync_driver/data_type_manager_impl.cc
@@ -76,10 +76,7 @@ void DataTypeManagerImpl::Configure(syncer::ModelTypeSet desired_types,
   if (reason == syncer::CONFIGURE_REASON_CATCH_UP)
     catch_up_in_progress_ = true;
 
-  if (reason == syncer::CONFIGURE_REASON_BACKUP_ROLLBACK)
-    desired_types.PutAll(syncer::ControlTypes());
-  else
-    desired_types.PutAll(syncer::CoreTypes());
+  desired_types.PutAll(syncer::CoreTypes());
 
   // Only allow control types and types that have controllers.
   syncer::ModelTypeSet filtered_desired_types;
diff --git a/components/sync_driver/data_type_manager_impl_unittest.cc b/components/sync_driver/data_type_manager_impl_unittest.cc
index 0374618..7f0b2d5 100644
--- a/components/sync_driver/data_type_manager_impl_unittest.cc
+++ b/components/sync_driver/data_type_manager_impl_unittest.cc
@@ -1286,21 +1286,6 @@ TEST_F(SyncDataTypeManagerImplTest, FilterDesiredTypes) {
   EXPECT_EQ(DataTypeManager::STOPPED, dtm_->state());
 }
 
-TEST_F(SyncDataTypeManagerImplTest, ConfigureForBackupRollback) {
-  AddController(BOOKMARKS);
-
-  SetConfigureStartExpectation();
-
-  ModelTypeSet expected_types = syncer::ControlTypes();
-  expected_types.Put(BOOKMARKS);
-  configurer_.set_expected_configure_types(
-      BackendDataTypeConfigurer::CONFIGURE_ACTIVE, expected_types);
-  dtm_->set_priority_types(expected_types);
-
-  dtm_->Configure(ModelTypeSet(BOOKMARKS),
-                  syncer::CONFIGURE_REASON_BACKUP_ROLLBACK);
-}
-
 TEST_F(SyncDataTypeManagerImplTest, ReenableAfterDataTypeError) {
   AddController(PREFERENCES);  // Will succeed.
   AddController(BOOKMARKS);    // Will be disabled due to datatype error.
diff --git a/components/sync_driver/device_info_service_unittest.cc b/components/sync_driver/device_info_service_unittest.cc
index d9c89cf..7556519 100644
--- a/components/sync_driver/device_info_service_unittest.cc
+++ b/components/sync_driver/device_info_service_unittest.cc
@@ -55,7 +55,6 @@ void AssertEqual(const DeviceInfoSpecifics& s1, const DeviceInfoSpecifics& s2) {
   ASSERT_EQ(s1.device_type(), s2.device_type());
   ASSERT_EQ(s1.sync_user_agent(), s2.sync_user_agent());
   ASSERT_EQ(s1.chrome_version(), s2.chrome_version());
-  ASSERT_EQ(s1.backup_timestamp(), s2.backup_timestamp());
   ASSERT_EQ(s1.signin_scoped_device_id(), s2.signin_scoped_device_id());
 }
 
@@ -189,7 +188,6 @@ class DeviceInfoServiceTest : public testing::Test,
         base::StringPrintf("sync user agent %d", label));
     specifics.set_chrome_version(
         base::StringPrintf("chrome version %d", label));
-    specifics.set_backup_timestamp(label);
     specifics.set_signin_scoped_device_id(
         base::StringPrintf("signin scoped device id %d", label));
     return specifics;
@@ -275,7 +273,6 @@ TEST_F(DeviceInfoServiceTest, NonEmptyStoreLoad) {
 
   scoped_ptr<WriteBatch> batch = store()->CreateWriteBatch();
   DeviceInfoSpecifics specifics(GenerateTestSpecifics());
-  specifics.set_backup_timestamp(6);
   store()->WriteData(batch.get(), "tag", specifics.SerializeAsString());
   store()->CommitWriteBatch(std::move(batch),
                             base::Bind(&AssertResultIsSuccess));
diff --git a/components/sync_driver/device_info_sync_service.cc b/components/sync_driver/device_info_sync_service.cc
index 77eaed4..009f6aa 100644
--- a/components/sync_driver/device_info_sync_service.cc
+++ b/components/sync_driver/device_info_sync_service.cc
@@ -59,8 +59,7 @@ void RecordDeviceIdChangedHistogram(const std::string& device_id_from_sync,
 
 DeviceInfoSyncService::DeviceInfoSyncService(
     LocalDeviceInfoProvider* local_device_info_provider)
-    : local_device_backup_time_(-1),
-      local_device_info_provider_(local_device_info_provider) {
+    : local_device_info_provider_(local_device_info_provider) {
   DCHECK(local_device_info_provider);
 }
 
@@ -108,19 +107,6 @@ SyncMergeResult DeviceInfoSyncService::MergeDataAndStartSyncing(
       scoped_ptr<DeviceInfo> synced_local_device_info =
           make_scoped_ptr(CreateDeviceInfo(*iter));
 
-      // Retrieve local device backup timestamp value from the sync data.
-      bool has_synced_backup_time =
-          iter->GetSpecifics().device_info().has_backup_timestamp();
-      int64_t synced_backup_time =
-          has_synced_backup_time
-              ? iter->GetSpecifics().device_info().backup_timestamp()
-              : -1;
-
-      // Overwrite |local_device_backup_time_| with this value if it
-      // hasn't been set yet.
-      if (!has_local_device_backup_time() && has_synced_backup_time) {
-        set_local_device_backup_time(synced_backup_time);
-      }
       // TODO(pavely): Remove histogram once device_id mismatch is understood
       // (crbug/481596).
       if (synced_local_device_info->signin_scoped_device_id() !=
@@ -130,12 +116,11 @@ SyncMergeResult DeviceInfoSyncService::MergeDataAndStartSyncing(
             local_device_info->signin_scoped_device_id());
       }
 
-      // Store the synced device info for the local device only
+      // Store the synced device info for the local device only if
       // it is the same as the local info. Otherwise store the local
       // device info and issue a change further below after finishing
       // processing the |initial_sync_data|.
-      if (synced_local_device_info->Equals(*local_device_info) &&
-          synced_backup_time == local_device_backup_time()) {
+      if (synced_local_device_info->Equals(*local_device_info)) {
         change_type = SyncChange::ACTION_INVALID;
       } else {
         num_items_updated++;
@@ -185,7 +170,6 @@ void DeviceInfoSyncService::StopSyncing(syncer::ModelType type) {
   all_data_.clear();
   sync_processor_.reset();
   error_handler_.reset();
-  clear_local_device_backup_time();
 
   if (was_syncing) {
     NotifyObservers();
@@ -284,56 +268,6 @@ void DeviceInfoSyncService::NotifyObservers() {
   FOR_EACH_OBSERVER(Observer, observers_, OnDeviceInfoChange());
 }
 
-void DeviceInfoSyncService::UpdateLocalDeviceBackupTime(
-    base::Time backup_time) {
-  set_local_device_backup_time(syncer::TimeToProtoTime(backup_time));
-
-  if (sync_processor_.get()) {
-    // Local device info must be available in advance
-    DCHECK(local_device_info_provider_->GetLocalDeviceInfo());
-    const std::string& local_id =
-        local_device_info_provider_->GetLocalDeviceInfo()->guid();
-
-    SyncDataMap::iterator iter = all_data_.find(local_id);
-    DCHECK(iter != all_data_.end());
-
-    syncer::SyncData& data = iter->second;
-    if (UpdateBackupTime(&data)) {
-      // Local device backup time has changed.
-      // Push changes to the server via the |sync_processor_|.
-      SyncChangeList change_list;
-      change_list.push_back(SyncChange(
-          FROM_HERE, syncer::SyncChange::ACTION_UPDATE, data));
-      sync_processor_->ProcessSyncChanges(FROM_HERE, change_list);
-    }
-  }
-}
-
-bool DeviceInfoSyncService::UpdateBackupTime(syncer::SyncData* sync_data) {
-  DCHECK(has_local_device_backup_time());
-  DCHECK(sync_data->GetSpecifics().has_device_info());
-  const sync_pb::DeviceInfoSpecifics& source_specifics =
-      sync_data->GetSpecifics().device_info();
-
-  if (!source_specifics.has_backup_timestamp() ||
-      source_specifics.backup_timestamp() != local_device_backup_time()) {
-    sync_pb::EntitySpecifics entity(sync_data->GetSpecifics());
-    entity.mutable_device_info()->set_backup_timestamp(
-        local_device_backup_time());
-    *sync_data = CreateLocalData(entity);
-
-    return true;
-  }
-
-  return false;
-}
-
-base::Time DeviceInfoSyncService::GetLocalDeviceBackupTime() const {
-  return has_local_device_backup_time()
-             ? syncer::ProtoTimeToTime(local_device_backup_time())
-             : base::Time();
-}
-
 SyncData DeviceInfoSyncService::CreateLocalData(const DeviceInfo* info) {
   sync_pb::EntitySpecifics entity;
   sync_pb::DeviceInfoSpecifics& specifics = *entity.mutable_device_info();
@@ -345,10 +279,6 @@ SyncData DeviceInfoSyncService::CreateLocalData(const DeviceInfo* info) {
   specifics.set_device_type(info->device_type());
   specifics.set_signin_scoped_device_id(info->signin_scoped_device_id());
 
-  if (has_local_device_backup_time()) {
-    specifics.set_backup_timestamp(local_device_backup_time());
-  }
-
   return CreateLocalData(entity);
 }
 
diff --git a/components/sync_driver/device_info_sync_service.h b/components/sync_driver/device_info_sync_service.h
index 7d529bb..6c82a12 100644
--- a/components/sync_driver/device_info_sync_service.h
+++ b/components/sync_driver/device_info_sync_service.h
@@ -52,13 +52,8 @@ class DeviceInfoSyncService : public syncer::SyncableService,
   void AddObserver(Observer* observer) override;
   void RemoveObserver(Observer* observer) override;
 
-  // Called to update local device backup time.
-  void UpdateLocalDeviceBackupTime(base::Time backup_time);
-  // Gets the most recently set local device backup time.
-  base::Time GetLocalDeviceBackupTime() const;
-
  private:
-  // Create SyncData from local DeviceInfo and |local_device_backup_time_|.
+  // Create SyncData from local DeviceInfo.
   syncer::SyncData CreateLocalData(const DeviceInfo* info);
   // Create SyncData from EntitySpecifics.
   static syncer::SyncData CreateLocalData(
@@ -74,25 +69,6 @@ class DeviceInfoSyncService : public syncer::SyncableService,
   // Notify all registered observers.
   void NotifyObservers();
 
-  // Updates backup time in place in |sync_data| if it is different than
-  // the one stored in |local_device_backup_time_|.
-  // Returns true if backup time was updated.
-  bool UpdateBackupTime(syncer::SyncData* sync_data);
-
-  // |local_device_backup_time_| accessors.
-  int64_t local_device_backup_time() const { return local_device_backup_time_; }
-  bool has_local_device_backup_time() const {
-    return local_device_backup_time_ >= 0;
-  }
-  void set_local_device_backup_time(int64_t value) {
-    local_device_backup_time_ = value;
-  }
-  void clear_local_device_backup_time() { local_device_backup_time_ = -1; }
-
-  // Local device last set backup time (in proto format).
-  // -1 if the value hasn't been specified
-  int64_t local_device_backup_time_;
-
   // |local_device_info_provider_| isn't owned.
   const LocalDeviceInfoProvider* const local_device_info_provider_;
 
diff --git a/components/sync_driver/device_info_sync_service_unittest.cc b/components/sync_driver/device_info_sync_service_unittest.cc
index 9592b71..2dffcbe 100644
--- a/components/sync_driver/device_info_sync_service_unittest.cc
+++ b/components/sync_driver/device_info_sync_service_unittest.cc
@@ -124,10 +124,6 @@ class DeviceInfoSyncServiceTest : public testing::Test,
     specifics.set_device_type(sync_pb::SyncEnums_DeviceType_TYPE_LINUX);
     specifics.set_signin_scoped_device_id("device_id");
 
-    if (backup_timestamp != 0) {
-      specifics.set_backup_timestamp(backup_timestamp);
-    }
-
     return SyncData::CreateRemoteData(1,
                                       entity,
                                       base::Time(),
@@ -418,152 +414,6 @@ TEST_F(DeviceInfoSyncServiceTest, ProcessChangesAfterUnsubscribing) {
   EXPECT_EQ(0, num_device_info_changed_callbacks_);
 }
 
-// Verifies setting backup timestamp after the initial sync.
-TEST_F(DeviceInfoSyncServiceTest, UpdateLocalDeviceBackupTime) {
-  // Shouldn't have backuptime initially.
-  base::Time backup_time = sync_service_->GetLocalDeviceBackupTime();
-  EXPECT_TRUE(backup_time.is_null());
-
-  // Perform the initial sync with empty data.
-  SyncMergeResult merge_result =
-      sync_service_->MergeDataAndStartSyncing(syncer::DEVICE_INFO,
-                                              SyncDataList(),
-                                              PassProcessor(),
-                                              CreateAndPassSyncErrorFactory());
-
-  // Should have local device after the initial sync.
-  EXPECT_EQ(1U, sync_processor_->change_list_size());
-  EXPECT_EQ(SyncChange::ACTION_ADD, sync_processor_->change_type_at(0));
-
-  // Shouldn't have backup time initially.
-  EXPECT_EQ("guid_1", sync_processor_->cache_guid_at(0));
-  EXPECT_FALSE(sync_processor_->device_info_at(0).has_backup_timestamp());
-
-  sync_service_->UpdateLocalDeviceBackupTime(base::Time::FromTimeT(1000));
-
-  // Should have local device info updated with the specified backup timestamp.
-  EXPECT_EQ(1U, sync_processor_->change_list_size());
-  EXPECT_EQ(SyncChange::ACTION_UPDATE, sync_processor_->change_type_at(0));
-  EXPECT_EQ("guid_1", sync_processor_->cache_guid_at(0));
-  EXPECT_TRUE(sync_processor_->device_info_at(0).has_backup_timestamp());
-
-  backup_time = syncer::ProtoTimeToTime(
-      sync_processor_->device_info_at(0).backup_timestamp());
-  EXPECT_EQ(1000, backup_time.ToTimeT());
-
-  // Also verify that we get the same backup time directly from the service.
-  backup_time = sync_service_->GetLocalDeviceBackupTime();
-  EXPECT_EQ(1000, backup_time.ToTimeT());
-}
-
-// Verifies setting backup timestamp prior to the initial sync.
-TEST_F(DeviceInfoSyncServiceTest, UpdateLocalDeviceBackupTimeBeforeSync) {
-  // Set the backup timestamp.
-  sync_service_->UpdateLocalDeviceBackupTime(base::Time::FromTimeT(2000));
-  // Verify that we get it back.
-  base::Time backup_time = sync_service_->GetLocalDeviceBackupTime();
-  EXPECT_EQ(2000, backup_time.ToTimeT());
-
-  // Now perform the initial sync with empty data.
-  SyncMergeResult merge_result =
-      sync_service_->MergeDataAndStartSyncing(syncer::DEVICE_INFO,
-                                              SyncDataList(),
-                                              PassProcessor(),
-                                              CreateAndPassSyncErrorFactory());
-
-  // Should have local device after the initial sync.
-  // Should have the backup timestamp set.
-  EXPECT_EQ(1U, sync_processor_->change_list_size());
-  EXPECT_EQ(SyncChange::ACTION_ADD, sync_processor_->change_type_at(0));
-  EXPECT_EQ("guid_1", sync_processor_->cache_guid_at(0));
-  EXPECT_TRUE(sync_processor_->device_info_at(0).has_backup_timestamp());
-
-  backup_time = syncer::ProtoTimeToTime(
-      sync_processor_->device_info_at(0).backup_timestamp());
-  EXPECT_EQ(2000, backup_time.ToTimeT());
-}
-
-// Verifies that the backup timestamp that comes in the intial sync data
-// gets preserved when there are no changes to the local device.
-TEST_F(DeviceInfoSyncServiceTest, PreserveBackupTimeWithMatchingLocalDevice) {
-  base::Time backup_time = base::Time::FromTimeT(3000);
-  SyncDataList sync_data;
-  sync_data.push_back(CreateRemoteData(
-      "guid_1", "client_1", syncer::TimeToProtoTime(backup_time)));
-
-  SyncMergeResult merge_result =
-      sync_service_->MergeDataAndStartSyncing(syncer::DEVICE_INFO,
-                                              sync_data,
-                                              PassProcessor(),
-                                              CreateAndPassSyncErrorFactory());
-
-  // Everything is matching so there should be no updates.
-  EXPECT_EQ(0U, sync_processor_->change_list_size());
-
-  // Verify that we get back the same time.
-  backup_time = sync_service_->GetLocalDeviceBackupTime();
-  EXPECT_EQ(3000, backup_time.ToTimeT());
-}
-
-// Verifies that the backup timestamp that comes in the intial sync data
-// gets merged with the local device data.
-TEST_F(DeviceInfoSyncServiceTest, MergeBackupTimeWithMatchingLocalDevice) {
-  base::Time backup_time = base::Time::FromTimeT(4000);
-  SyncDataList sync_data;
-  sync_data.push_back(CreateRemoteData(
-      "guid_1", "foo_1", syncer::TimeToProtoTime(backup_time)));
-
-  SyncMergeResult merge_result =
-      sync_service_->MergeDataAndStartSyncing(syncer::DEVICE_INFO,
-                                              sync_data,
-                                              PassProcessor(),
-                                              CreateAndPassSyncErrorFactory());
-
-  // Should be one change because of the client name mismatch.
-  // However the backup time passed in the initial data should be merged into
-  // the change.
-  EXPECT_EQ(1U, sync_processor_->change_list_size());
-
-  EXPECT_EQ(SyncChange::ACTION_UPDATE, sync_processor_->change_type_at(0));
-  EXPECT_EQ("guid_1", sync_processor_->cache_guid_at(0));
-  EXPECT_EQ("client_1", sync_processor_->client_name_at(0));
-
-  backup_time = syncer::ProtoTimeToTime(
-      sync_processor_->device_info_at(0).backup_timestamp());
-  EXPECT_EQ(4000, backup_time.ToTimeT());
-}
-
-// Verifies that mismatching backup timestamp generates an update even
-// when the rest of local device data is matching.
-TEST_F(DeviceInfoSyncServiceTest,
-       MergeMismatchingBackupTimeWithMatchingLocalDevice) {
-  base::Time backup_time = base::Time::FromTimeT(5000);
-  SyncDataList sync_data;
-  sync_data.push_back(CreateRemoteData(
-      "guid_1", "client_1", syncer::TimeToProtoTime(backup_time)));
-
-  // Set the backup timestamp different than the one in the sync data.
-  sync_service_->UpdateLocalDeviceBackupTime(base::Time::FromTimeT(6000));
-
-  SyncMergeResult merge_result =
-      sync_service_->MergeDataAndStartSyncing(syncer::DEVICE_INFO,
-                                              sync_data,
-                                              PassProcessor(),
-                                              CreateAndPassSyncErrorFactory());
-
-  // Should generate and update due to timestamp mismatch.
-  // The locally set timestamp wins.
-  EXPECT_EQ(1U, sync_processor_->change_list_size());
-
-  EXPECT_EQ(SyncChange::ACTION_UPDATE, sync_processor_->change_type_at(0));
-  EXPECT_EQ("guid_1", sync_processor_->cache_guid_at(0));
-  EXPECT_EQ("client_1", sync_processor_->client_name_at(0));
-
-  backup_time = syncer::ProtoTimeToTime(
-      sync_processor_->device_info_at(0).backup_timestamp());
-  EXPECT_EQ(6000, backup_time.ToTimeT());
-}
-
 }  // namespace
 
 }  // namespace sync_driver
diff --git a/components/sync_driver/fake_sync_client.cc b/components/sync_driver/fake_sync_client.cc
index 2b65860..2dce0ce 100644
--- a/components/sync_driver/fake_sync_client.cc
+++ b/components/sync_driver/fake_sync_client.cc
@@ -12,8 +12,6 @@ namespace sync_driver {
 
 namespace {
 
-void DummyClearBrowsingDataCallback(base::Time start, base::Time end) {}
-
 void DummyRegisterPlatformTypesCallback(SyncService* sync_service,
                                         syncer::ModelTypeSet,
                                         syncer::ModelTypeSet) {}
@@ -52,10 +50,6 @@ history::HistoryService* FakeSyncClient::GetHistoryService() {
   return nullptr;
 }
 
-ClearBrowsingDataCallback FakeSyncClient::GetClearBrowsingDataCallback() {
-  return base::Bind(&DummyClearBrowsingDataCallback);
-}
-
 base::Closure FakeSyncClient::GetPasswordStateChangedCallback() {
   return base::Bind(&base::DoNothing);
 }
diff --git a/components/sync_driver/fake_sync_client.h b/components/sync_driver/fake_sync_client.h
index f394b6d..7aa7251 100644
--- a/components/sync_driver/fake_sync_client.h
+++ b/components/sync_driver/fake_sync_client.h
@@ -25,7 +25,6 @@ class FakeSyncClient : public SyncClient {
   bookmarks::BookmarkModel* GetBookmarkModel() override;
   favicon::FaviconService* GetFaviconService() override;
   history::HistoryService* GetHistoryService() override;
-  ClearBrowsingDataCallback GetClearBrowsingDataCallback() override;
   base::Closure GetPasswordStateChangedCallback() override;
   sync_driver::SyncApiComponentFactory::RegisterDataTypesMethod
   GetRegisterPlatformTypesCallback() override;
diff --git a/components/sync_driver/glue/sync_backend_host_impl_unittest.cc b/components/sync_driver/glue/sync_backend_host_impl_unittest.cc
index 1968558..f01f740 100644
--- a/components/sync_driver/glue/sync_backend_host_impl_unittest.cc
+++ b/components/sync_driver/glue/sync_backend_host_impl_unittest.cc
@@ -120,8 +120,7 @@ class MockSyncFrontend : public sync_driver::SyncFrontend {
 class FakeSyncManagerFactory : public syncer::SyncManagerFactory {
  public:
   explicit FakeSyncManagerFactory(FakeSyncManager** fake_manager)
-     : SyncManagerFactory(NORMAL),
-       fake_manager_(fake_manager) {
+     : fake_manager_(fake_manager) {
     *fake_manager_ = NULL;
   }
   ~FakeSyncManagerFactory() override {}
diff --git a/components/sync_driver/pref_names.cc b/components/sync_driver/pref_names.cc
index 550b927..ef7ab29 100644
--- a/components/sync_driver/pref_names.cc
+++ b/components/sync_driver/pref_names.cc
@@ -91,9 +91,6 @@ const char kSyncSessionsGUID[] = "sync.session_sync_guid";
 const char kSyncSpareBootstrapToken[] = "sync.spare_bootstrap_token";
 #endif  // defined(OS_CHROMEOS)
 
-// Stores how many times to try rollback before giving up.
-const char kSyncRemainingRollbackTries[] = "sync.remaining_rollback_tries";
-
 // Stores the timestamp of first sync.
 const char kSyncFirstSyncTime[] = "sync.first_sync_time";
 
diff --git a/components/sync_driver/pref_names.h b/components/sync_driver/pref_names.h
index 3209780..d3ecf97 100644
--- a/components/sync_driver/pref_names.h
+++ b/components/sync_driver/pref_names.h
@@ -64,7 +64,6 @@ extern const char kSyncSessionsGUID[];
 extern const char kSyncSpareBootstrapToken[];
 #endif  // defined(OS_CHROMEOS)
 
-extern const char kSyncRemainingRollbackTries[];
 extern const char kSyncFirstSyncTime[];
 
 extern const char kSyncPassphrasePrompted[];
diff --git a/components/sync_driver/startup_controller.cc b/components/sync_driver/startup_controller.cc
index f22f31f..4db2bb2 100644
--- a/components/sync_driver/startup_controller.cc
+++ b/components/sync_driver/startup_controller.cc
@@ -159,10 +159,7 @@ bool StartupController::TryStart() {
   // defer the heavy lifting for sync init until things have calmed down.
   if (sync_prefs_->IsFirstSetupComplete()) {
     // For first time, defer start if data type hasn't requested sync to avoid
-    // stressing browser start. If |first_start_| is false, most likely the
-    // first attempt to start is intercepted by backup. When backup finishes,
-    // TryStart() is called again and we should start immediately to avoid
-    // unnecessary delay.
+    // stressing browser start.
     if (!received_start_request_ && first_start_)
       return StartUp(STARTUP_BACKEND_DEFERRED);
     else
diff --git a/components/sync_driver/sync_client.h b/components/sync_driver/sync_client.h
index a2e0558..2982a4d 100644
--- a/components/sync_driver/sync_client.h
+++ b/components/sync_driver/sync_client.h
@@ -9,7 +9,6 @@
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
-#include "base/time/time.h"
 #include "components/sync_driver/sync_api_component_factory.h"
 #include "sync/internal_api/public/base/model_type.h"
 #include "sync/internal_api/public/engine/model_safe_worker.h"
@@ -52,8 +51,6 @@ namespace sync_driver {
 
 class SyncService;
 
-typedef base::Callback<void(base::Time, base::Time)> ClearBrowsingDataCallback;
-
 // Interface for clients of the Sync API to plumb through necessary dependent
 // components. This interface is purely for abstracting dependencies, and
 // should not contain any non-trivial functional logic.
@@ -79,10 +76,6 @@ class SyncClient {
   virtual favicon::FaviconService* GetFaviconService() = 0;
   virtual history::HistoryService* GetHistoryService() = 0;
 
-  // Returns a callback that will be invoked when the sync service wishes to
-  // have browsing data cleared.
-  virtual ClearBrowsingDataCallback GetClearBrowsingDataCallback() = 0;
-
   // Returns a callback that will register the types specific to the current
   // platform.
   virtual sync_driver::SyncApiComponentFactory::RegisterDataTypesMethod
diff --git a/components/sync_driver/sync_driver_switches.cc b/components/sync_driver/sync_driver_switches.cc
index 15cde97..498a82b 100644
--- a/components/sync_driver/sync_driver_switches.cc
+++ b/components/sync_driver/sync_driver_switches.cc
@@ -10,16 +10,10 @@ namespace switches {
 const char kSyncDeferredStartupTimeoutSeconds[] =
     "sync-deferred-startup-timeout-seconds";
 
-// Disable data backup when user's not signed in.
-const char kSyncDisableBackup[] = "disable-sync-backup";
-
 // Enables deferring sync backend initialization until user initiated changes
 // occur.
 const char kSyncDisableDeferredStartup[] = "sync-disable-deferred-startup";
 
-// Disable sync rollback.
-const char kSyncDisableRollback[] = "disable-sync-rollback";
-
 // Enables clearing of sync data when a user enables passphrase encryption.
 const char kSyncEnableClearDataOnPassphraseEncryption[] =
     "enable-clear-sync-data-on-passphrase-encryption";
diff --git a/components/sync_driver/sync_driver_switches.h b/components/sync_driver/sync_driver_switches.h
index caeb038..9528aa6 100644
--- a/components/sync_driver/sync_driver_switches.h
+++ b/components/sync_driver/sync_driver_switches.h
@@ -12,9 +12,7 @@ namespace switches {
 // All switches in alphabetical order. The switches should be documented
 // alongside the definition of their values in the .cc file.
 extern const char kSyncDeferredStartupTimeoutSeconds[];
-extern const char kSyncDisableBackup[];
 extern const char kSyncDisableDeferredStartup[];
-extern const char kSyncDisableRollback[];
 extern const char kSyncEnableClearDataOnPassphraseEncryption[];
 extern const char kSyncEnableGetUpdateAvoidance[];
 extern const char kSyncEnableUSSDeviceInfo[];
diff --git a/components/sync_driver/sync_prefs.cc b/components/sync_driver/sync_prefs.cc
index e029142..185a122 100644
--- a/components/sync_driver/sync_prefs.cc
+++ b/components/sync_driver/sync_prefs.cc
@@ -79,7 +79,6 @@ void SyncPrefs::RegisterProfilePrefs(
 
   registry->RegisterBooleanPref(prefs::kSyncHasAuthError, false);
   registry->RegisterStringPref(prefs::kSyncSessionsGUID, std::string());
-  registry->RegisterIntegerPref(prefs::kSyncRemainingRollbackTries, 0);
   registry->RegisterBooleanPref(prefs::kSyncPassphrasePrompted, false);
   registry->RegisterIntegerPref(prefs::kSyncMemoryPressureWarningCount, -1);
   registry->RegisterBooleanPref(prefs::kSyncShutdownCleanly, false);
@@ -337,14 +336,6 @@ void SyncPrefs::SetSpareBootstrapToken(const std::string& token) {
 }
 #endif
 
-int SyncPrefs::GetRemainingRollbackTries() const {
-  return pref_service_->GetInteger(prefs::kSyncRemainingRollbackTries);
-}
-
-void SyncPrefs::SetRemainingRollbackTries(int times) {
-  pref_service_->SetInteger(prefs::kSyncRemainingRollbackTries, times);
-}
-
 void SyncPrefs::OnSyncManagedPrefChanged() {
   DCHECK(CalledOnValidThread());
   FOR_EACH_OBSERVER(SyncPrefObserver,
diff --git a/components/sync_driver/sync_prefs.h b/components/sync_driver/sync_prefs.h
index 96f1a8e..4f2c65e 100644
--- a/components/sync_driver/sync_prefs.h
+++ b/components/sync_driver/sync_prefs.h
@@ -133,10 +133,6 @@ class SyncPrefs : NON_EXPORTED_BASE(public base::NonThreadSafe),
   void SetSpareBootstrapToken(const std::string& token);
 #endif
 
-  // Get/Set number of rollback attempts allowed.
-  virtual int GetRemainingRollbackTries() const;
-  virtual void SetRemainingRollbackTries(int times);
-
   // Get/set/clear first sync time of current user. Used to roll back browsing
   // data later when user signs out.
   base::Time GetFirstSyncTime() const;
diff --git a/components/sync_driver/sync_service.h b/components/sync_driver/sync_service.h
index e722444..76efc25 100644
--- a/components/sync_driver/sync_service.h
+++ b/components/sync_driver/sync_service.h
@@ -99,8 +99,6 @@ class SyncService : public DataTypeEncryptionHandler {
   // an initial configuration has successfully completed, although there may
   // be datatype specific, auth, or other transient errors. To see which
   // datetypes are actually syncing, see GetActiveTypes() below.
-  // Note that if sync is in backup or rollback mode, IsSyncActive() will be
-  // false.
   virtual bool IsSyncActive() const = 0;
 
   // Triggers a GetUpdates call for the specified |types|, pulling any new data
diff --git a/components/user_prefs/tracked/pref_hash_filter.cc b/components/user_prefs/tracked/pref_hash_filter.cc
index 6d8e628..a9b4183 100644
--- a/components/user_prefs/tracked/pref_hash_filter.cc
+++ b/components/user_prefs/tracked/pref_hash_filter.cc
@@ -36,6 +36,8 @@ void CleanupDeprecatedTrackedPreferences(
       "safebrowsing.incident_report_sent",
       // TODO(mad): Remove in M48+.
       "software_reporter.prompt_reason",
+      // TODO(zea): Remove in M52+,
+      "sync.remaining_rollback_tries"
   };
 
   for (size_t i = 0; i < arraysize(kDeprecatedTrackedPreferences); ++i) {
diff --git a/ios/chrome/browser/sync/ios_chrome_sync_client.h b/ios/chrome/browser/sync/ios_chrome_sync_client.h
index d1535f8..a398c71 100644
--- a/ios/chrome/browser/sync/ios_chrome_sync_client.h
+++ b/ios/chrome/browser/sync/ios_chrome_sync_client.h
@@ -38,8 +38,6 @@ class IOSChromeSyncClient : public sync_driver::SyncClient {
   bookmarks::BookmarkModel* GetBookmarkModel() override;
   favicon::FaviconService* GetFaviconService() override;
   history::HistoryService* GetHistoryService() override;
-  sync_driver::ClearBrowsingDataCallback GetClearBrowsingDataCallback()
-      override;
   base::Closure GetPasswordStateChangedCallback() override;
   sync_driver::SyncApiComponentFactory::RegisterDataTypesMethod
   GetRegisterPlatformTypesCallback() override;
diff --git a/ios/chrome/browser/sync/ios_chrome_sync_client.mm b/ios/chrome/browser/sync/ios_chrome_sync_client.mm
index dc5b80e..89007d3 100644
--- a/ios/chrome/browser/sync/ios_chrome_sync_client.mm
+++ b/ios/chrome/browser/sync/ios_chrome_sync_client.mm
@@ -199,12 +199,6 @@ autofill::PersonalDataManager* IOSChromeSyncClient::GetPersonalDataManager() {
   return PersonalDataManagerFactory::GetForBrowserState(browser_state_);
 }
 
-sync_driver::ClearBrowsingDataCallback
-IOSChromeSyncClient::GetClearBrowsingDataCallback() {
-  return base::Bind(&IOSChromeSyncClient::ClearBrowsingData,
-                    base::Unretained(this));
-}
-
 base::Closure IOSChromeSyncClient::GetPasswordStateChangedCallback() {
   return base::Bind(
       &IOSChromePasswordStoreFactory::OnPasswordsSyncedStatePotentiallyChanged,
@@ -384,11 +378,6 @@ IOSChromeSyncClient::GetSyncApiComponentFactory() {
   return component_factory_.get();
 }
 
-void IOSChromeSyncClient::ClearBrowsingData(base::Time start, base::Time end) {
-  // This method should never be called on iOS.
-  NOTREACHED();
-}
-
 void IOSChromeSyncClient::SetSyncApiComponentFactoryForTesting(
     scoped_ptr<sync_driver::SyncApiComponentFactory> component_factory) {
   component_factory_ = std::move(component_factory);
diff --git a/sync/BUILD.gn b/sync/BUILD.gn
index dfa0fae..f28fee8 100644
--- a/sync/BUILD.gn
+++ b/sync/BUILD.gn
@@ -297,8 +297,6 @@ source_set("sync_core") {
     "internal_api/read_node.cc",
     "internal_api/read_transaction.cc",
     "internal_api/shared_model_type_processor.cc",
-    "internal_api/sync_backup_manager.cc",
-    "internal_api/sync_backup_manager.h",
     "internal_api/sync_context.cc",
     "internal_api/sync_context_proxy.cc",
     "internal_api/sync_context_proxy_impl.cc",
@@ -309,10 +307,6 @@ source_set("sync_core") {
     "internal_api/sync_manager_factory.cc",
     "internal_api/sync_manager_impl.cc",
     "internal_api/sync_manager_impl.h",
-    "internal_api/sync_rollback_manager.cc",
-    "internal_api/sync_rollback_manager.h",
-    "internal_api/sync_rollback_manager_base.cc",
-    "internal_api/sync_rollback_manager_base.h",
     "internal_api/syncapi_internal.cc",
     "internal_api/syncapi_internal.h",
     "internal_api/syncapi_server_connection_manager.cc",
@@ -348,8 +342,6 @@ source_set("sync_core") {
     "sessions/sync_session.h",
     "sessions/sync_session_context.cc",
     "sessions/sync_session_context.h",
-    "syncable/deferred_on_disk_directory_backing_store.cc",
-    "syncable/deferred_on_disk_directory_backing_store.h",
     "syncable/dir_open_result.h",
     "syncable/directory.cc",
     "syncable/directory.h",
@@ -666,12 +658,9 @@ test("sync_unit_tests") {
     "internal_api/public/util/proto_value_ptr_unittest.cc",
     "internal_api/public/util/weak_handle_unittest.cc",
     "internal_api/shared_model_type_processor_unittest.cc",
-    "internal_api/sync_backup_manager_unittest.cc",
     "internal_api/sync_context_proxy_impl_unittest.cc",
     "internal_api/sync_encryption_handler_impl_unittest.cc",
     "internal_api/sync_manager_impl_unittest.cc",
-    "internal_api/sync_rollback_manager_base_unittest.cc",
-    "internal_api/sync_rollback_manager_unittest.cc",
     "internal_api/syncapi_server_connection_manager_unittest.cc",
     "js/js_event_details_unittest.cc",
     "js/sync_js_controller_unittest.cc",
@@ -680,7 +669,6 @@ test("sync_unit_tests") {
     "sessions/model_type_registry_unittest.cc",
     "sessions/nudge_tracker_unittest.cc",
     "sessions/status_controller_unittest.cc",
-    "syncable/deferred_on_disk_directory_backing_store_unittest.cc",
     "syncable/directory_backing_store_unittest.cc",
     "syncable/directory_unittest.cc",
     "syncable/directory_unittest.h",
diff --git a/sync/engine/sync_scheduler_impl.cc b/sync/engine/sync_scheduler_impl.cc
index f126473..cc5e4a7 100644
--- a/sync/engine/sync_scheduler_impl.cc
+++ b/sync/engine/sync_scheduler_impl.cc
@@ -58,7 +58,6 @@ bool ShouldRequestEarlyExit(const SyncProtocolError& error) {
     case CLIENT_DATA_OBSOLETE:
     case CLEAR_PENDING:
     case DISABLED_BY_ADMIN:
-    case USER_ROLLBACK:
       // If we send terminate sync early then |sync_cycle_ended| notification
       // would not be sent. If there were no actions then |ACTIONABLE_ERROR|
       // notification wouldnt be sent either. Then the UI layer would be left
diff --git a/sync/engine/syncer_proto_util.cc b/sync/engine/syncer_proto_util.cc
index 306137b..66c4013 100644
--- a/sync/engine/syncer_proto_util.cc
+++ b/sync/engine/syncer_proto_util.cc
@@ -124,8 +124,6 @@ SyncProtocolErrorType PBErrorTypeToSyncProtocolErrorType(
       return MIGRATION_DONE;
     case sync_pb::SyncEnums::DISABLED_BY_ADMIN:
       return DISABLED_BY_ADMIN;
-    case sync_pb::SyncEnums::USER_ROLLBACK:
-      return USER_ROLLBACK;
     case sync_pb::SyncEnums::PARTIAL_FAILURE:
       return PARTIAL_FAILURE;
     case sync_pb::SyncEnums::CLIENT_DATA_OBSOLETE:
@@ -193,8 +191,6 @@ SyncProtocolError ErrorCodeToSyncProtocolError(
     error.action = RESET_LOCAL_SYNC_DATA;
   } else if (error_type == sync_pb::SyncEnums::DISABLED_BY_ADMIN) {
     error.action = STOP_SYNC_FOR_DISABLED_ACCOUNT;
-  } else if (error_type == sync_pb::SyncEnums::USER_ROLLBACK) {
-    error.action = DISABLE_SYNC_AND_ROLLBACK;
   }  // There is no other action we can compute for legacy server.
   return error;
 }
@@ -498,8 +494,6 @@ SyncerError SyncerProtoUtil::PostClientToServerMessage(
       return SERVER_RETURN_NOT_MY_BIRTHDAY;
     case DISABLED_BY_ADMIN:
       return SERVER_RETURN_DISABLED_BY_ADMIN;
-    case USER_ROLLBACK:
-      return SERVER_RETURN_USER_ROLLBACK;
     case PARTIAL_FAILURE:
       // This only happens when partial throttling during GetUpdates.
       if (!sync_protocol_error.error_data_types.Empty()) {
diff --git a/sync/internal_api/internal_components_factory_impl.cc b/sync/internal_api/internal_components_factory_impl.cc
index 4f2f32e..65fcfaf 100644
--- a/sync/internal_api/internal_components_factory_impl.cc
+++ b/sync/internal_api/internal_components_factory_impl.cc
@@ -11,7 +11,6 @@
 #include "sync/engine/syncer.h"
 #include "sync/engine/sync_scheduler_impl.h"
 #include "sync/sessions/sync_session_context.h"
-#include "sync/syncable/deferred_on_disk_directory_backing_store.h"
 #include "sync/syncable/on_disk_directory_backing_store.h"
 
 using base::TimeDelta;
@@ -68,10 +67,6 @@ InternalComponentsFactoryImpl::BuildDirectoryBackingStore(
   if (storage == STORAGE_ON_DISK) {
     return scoped_ptr<syncable::DirectoryBackingStore>(
         new syncable::OnDiskDirectoryBackingStore(dir_name, backing_filepath));
-  } else if (storage == STORAGE_ON_DISK_DEFERRED) {
-    return scoped_ptr<syncable::DirectoryBackingStore>(
-        new syncable::DeferredOnDiskDirectoryBackingStore(dir_name,
-                                                          backing_filepath));
   } else {
     NOTREACHED();
     return scoped_ptr<syncable::DirectoryBackingStore>();
diff --git a/sync/internal_api/public/configure_reason.h b/sync/internal_api/public/configure_reason.h
index 8fbbc4e..4d015b9 100644
--- a/sync/internal_api/public/configure_reason.h
+++ b/sync/internal_api/public/configure_reason.h
@@ -33,9 +33,6 @@ enum ConfigureReason {
   // cryptographer errors/resolutions.
   CONFIGURE_REASON_CRYPTO,
 
-  // Configure data types for backup/rollback.
-  CONFIGURE_REASON_BACKUP_ROLLBACK,
-
   // The client is configuring because of a programmatic type enable/disable,
   // such as when an error is encountered/resolved.
   CONFIGURE_REASON_PROGRAMMATIC,
diff --git a/sync/internal_api/public/internal_components_factory.h b/sync/internal_api/public/internal_components_factory.h
index f077af0..fee9bec 100644
--- a/sync/internal_api/public/internal_components_factory.h
+++ b/sync/internal_api/public/internal_components_factory.h
@@ -80,9 +80,6 @@ class SYNC_EXPORT InternalComponentsFactory {
     // Use this if you want BuildDirectoryBackingStore to create/use a real
     // on disk store.
     STORAGE_ON_DISK,
-    // Use this to defer creating on-disk database until
-    // DirectoryBackingStore::SaveChanges() is called.
-    STORAGE_ON_DISK_DEFERRED,
     // Use this to test the case where a directory fails to load.
     STORAGE_INVALID
   };
diff --git a/sync/internal_api/public/shutdown_reason.h b/sync/internal_api/public/shutdown_reason.h
index f913eec..604dc0e 100644
--- a/sync/internal_api/public/shutdown_reason.h
+++ b/sync/internal_api/public/shutdown_reason.h
@@ -14,8 +14,6 @@ enum ShutdownReason {
   STOP_SYNC,         // Sync is asked to stop, e.g. due to scarce resource.
   DISABLE_SYNC,      // Sync is disabled, e.g. user sign out, dashboard clear.
   BROWSER_SHUTDOWN,  // Browser is closed.
-  SWITCH_MODE_SYNC,  // Engine is shut down and a new engine will start in
-                     // sync mode.
 };
 
 }  // namespace syncer
diff --git a/sync/internal_api/public/sync_manager_factory.h b/sync/internal_api/public/sync_manager_factory.h
index ef6ee6b..feb9e8b 100644
--- a/sync/internal_api/public/sync_manager_factory.h
+++ b/sync/internal_api/public/sync_manager_factory.h
@@ -15,22 +15,15 @@ namespace syncer {
 
 class SyncManager;
 
-// Helper class to allow dependency injection of the SyncManager.
+// Helper class to allow dependency injection of the SyncManager in tests.
 class SYNC_EXPORT SyncManagerFactory {
  public:
-  enum MANAGER_TYPE {
-    NORMAL,     // Normal sync manager
-    BACKUP,     // Backup sync manager
-    ROLLBACK,   // Rollback sync manager
-  };
-
-  explicit SyncManagerFactory(MANAGER_TYPE type);
+  SyncManagerFactory();
   virtual ~SyncManagerFactory();
 
   virtual scoped_ptr<SyncManager> CreateSyncManager(const std::string& name);
 
  private:
-  MANAGER_TYPE type_;
   DISALLOW_COPY_AND_ASSIGN(SyncManagerFactory);
 };
 
diff --git a/sync/internal_api/sync_backup_manager.cc b/sync/internal_api/sync_backup_manager.cc
deleted file mode 100644
index 9151e52..0000000
--- a/sync/internal_api/sync_backup_manager.cc
+++ /dev/null
@@ -1,151 +0,0 @@
-// Copyright 2014 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "sync/internal_api/sync_backup_manager.h"
-
-#include <stdint.h>
-
-#include <vector>
-
-#include "sync/internal_api/public/read_node.h"
-#include "sync/internal_api/public/write_transaction.h"
-#include "sync/syncable/directory.h"
-#include "sync/syncable/mutable_entry.h"
-#include "url/gurl.h"
-
-namespace syncer {
-
-SyncBackupManager::SyncBackupManager()
-    : in_normalization_(false) {
-}
-
-SyncBackupManager::~SyncBackupManager() {
-}
-
-void SyncBackupManager::Init(InitArgs* args) {
-  if (SyncRollbackManagerBase::InitInternal(
-          args->database_location,
-          args->internal_components_factory.get(),
-          InternalComponentsFactory::STORAGE_ON_DISK_DEFERRED,
-          args->unrecoverable_error_handler,
-          args->report_unrecoverable_error_function)) {
-    GetUserShare()->directory->CollectMetaHandleCounts(
-        &status_.num_entries_by_type, &status_.num_to_delete_entries_by_type);
-
-    HideSyncPreference(PRIORITY_PREFERENCES);
-    HideSyncPreference(PREFERENCES);
-  }
-}
-
-void SyncBackupManager::SaveChanges() {
-  if (initialized())
-    NormalizeEntries();
-}
-
-SyncStatus SyncBackupManager::GetDetailedStatus() const {
-  return status_;
-}
-
-ModelTypeSet SyncBackupManager::HandleTransactionEndingChangeEvent(
-    const syncable::ImmutableWriteTransactionInfo& write_transaction_info,
-    syncable::BaseTransaction* trans) {
-  ModelTypeSet types;
-  if (in_normalization_) {
-    // Skip if in our own WriteTransaction from NormalizeEntries().
-    in_normalization_ = false;
-    return types;
-  }
-
-  for (syncable::EntryKernelMutationMap::const_iterator it =
-      write_transaction_info.Get().mutations.Get().begin();
-      it != write_transaction_info.Get().mutations.Get().end(); ++it) {
-    int64_t id = it->first;
-    if (unsynced_.find(id) == unsynced_.end()) {
-      unsynced_.insert(id);
-
-      const syncable::EntryKernel& e = it->second.mutated;
-      ModelType type = e.GetModelType();
-      types.Put(type);
-      if (!e.ref(syncable::ID).ServerKnows())
-        status_.num_entries_by_type[type]++;
-      if (e.ref(syncable::IS_DEL))
-        status_.num_to_delete_entries_by_type[type]++;
-    }
-  }
-  return types;
-}
-
-void SyncBackupManager::NormalizeEntries() {
-  WriteTransaction trans(FROM_HERE, GetUserShare());
-  in_normalization_ = true;
-  for (std::set<int64_t>::const_iterator it = unsynced_.begin();
-       it != unsynced_.end(); ++it) {
-    syncable::MutableEntry entry(trans.GetWrappedWriteTrans(),
-                                 syncable::GET_BY_HANDLE, *it);
-    CHECK(entry.good());
-
-    if (!entry.GetId().ServerKnows())
-      entry.PutId(syncable::Id::CreateFromServerId(entry.GetId().value()));
-    if (!entry.GetParentId().IsNull() && !entry.GetParentId().ServerKnows()) {
-      entry.PutParentIdPropertyOnly(syncable::Id::CreateFromServerId(
-          entry.GetParentId().value()));
-    }
-    entry.PutBaseVersion(1);
-    entry.PutIsUnsynced(false);
-  }
-  unsynced_.clear();
-}
-
-void SyncBackupManager::HideSyncPreference(ModelType type) {
-  WriteTransaction trans(FROM_HERE, GetUserShare());
-  ReadNode pref_root(&trans);
-  if (BaseNode::INIT_OK != pref_root.InitTypeRoot(type))
-    return;
-
-  std::vector<int64_t> pref_ids;
-  pref_root.GetChildIds(&pref_ids);
-  for (uint32_t i = 0; i < pref_ids.size(); ++i) {
-    syncable::MutableEntry entry(trans.GetWrappedWriteTrans(),
-                                 syncable::GET_BY_HANDLE, pref_ids[i]);
-    if (entry.good()) {
-      // HACKY: Set IS_DEL to true to remove entry from parent-children
-      // index so that it's not returned when syncable service asks
-      // for sync data. Syncable service then creates entry for local
-      // model. Then the existing entry is undeleted and set to local value
-      // because it has the same unique client tag.
-      entry.PutIsDel(true);
-      entry.PutIsUnsynced(false);
-
-      // Don't persist on disk so that if backup is aborted before receiving
-      // local preference values, values in sync DB are saved.
-      GetUserShare()->directory->UnmarkDirtyEntry(
-          trans.GetWrappedWriteTrans(), &entry);
-    }
-  }
-}
-
-void SyncBackupManager::ShutdownOnSyncThread(ShutdownReason reason) {
-  if (reason == SWITCH_MODE_SYNC) {
-    NormalizeEntries();
-    GetUserShare()->directory->SaveChanges();
-  }
-
-  SyncRollbackManagerBase::ShutdownOnSyncThread(reason);
-}
-
-void SyncBackupManager::RegisterDirectoryTypeDebugInfoObserver(
-    syncer::TypeDebugInfoObserver* observer) {}
-
-void SyncBackupManager::UnregisterDirectoryTypeDebugInfoObserver(
-    syncer::TypeDebugInfoObserver* observer) {}
-
-bool SyncBackupManager::HasDirectoryTypeDebugInfoObserver(
-    syncer::TypeDebugInfoObserver* observer) { return false; }
-
-void SyncBackupManager::RequestEmitDebugInfo() {}
-
-void SyncBackupManager::ClearServerData(
-    const ClearServerDataCallback& callback) {}
-
-}  // namespace syncer
diff --git a/sync/internal_api/sync_backup_manager.h b/sync/internal_api/sync_backup_manager.h
deleted file mode 100644
index e7e50fa..0000000
--- a/sync/internal_api/sync_backup_manager.h
+++ /dev/null
@@ -1,70 +0,0 @@
-// Copyright 2014 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef SYNC_INTERNAL_API_SYNC_BACKUP_MANAGER_H_
-#define SYNC_INTERNAL_API_SYNC_BACKUP_MANAGER_H_
-
-#include <stdint.h>
-
-#include <set>
-
-#include "base/macros.h"
-#include "sync/internal_api/sync_rollback_manager_base.h"
-#include "url/gurl.h"
-
-namespace syncer {
-
-// SyncBackupManager runs before user signs in to sync to back up user's data
-// before sync starts. The data that's backed up can be used to restore user's
-// settings to pre-sync state.
-class SYNC_EXPORT SyncBackupManager : public SyncRollbackManagerBase {
- public:
-  SyncBackupManager();
-  ~SyncBackupManager() override;
-
-  // SyncManager implementation.
-  void Init(InitArgs* args) override;
-  void SaveChanges() override;
-  SyncStatus GetDetailedStatus() const override;
-  void ShutdownOnSyncThread(ShutdownReason reason) override;
-
-  // DirectoryChangeDelegate implementation.
-  ModelTypeSet HandleTransactionEndingChangeEvent(
-      const syncable::ImmutableWriteTransactionInfo& write_transaction_info,
-      syncable::BaseTransaction* trans) override;
-
-  void RegisterDirectoryTypeDebugInfoObserver(
-      syncer::TypeDebugInfoObserver* observer) override;
-  void UnregisterDirectoryTypeDebugInfoObserver(
-      syncer::TypeDebugInfoObserver* observer) override;
-  bool HasDirectoryTypeDebugInfoObserver(
-      syncer::TypeDebugInfoObserver* observer) override;
-  void RequestEmitDebugInfo() override;
-  void ClearServerData(const ClearServerDataCallback& callback) override;
-
- private:
-  // Replaces local IDs with server IDs and clear unsynced bit of modified
-  // entries.
-  void NormalizeEntries();
-
-  // Manipulate preference nodes so that they'll be overwritten by local
-  // preference values during model association, i.e. local wins instead of
-  // server wins. This is for preventing backup from changing preferences in
-  // case backup DB has hijacked preferences.
-  void HideSyncPreference(ModelType pref_type);
-
-  // Handles of unsynced entries caused by local model changes.
-  std::set<int64_t> unsynced_;
-
-  // True if NormalizeEntries() is being called.
-  bool in_normalization_;
-
-  SyncStatus status_;
-
-  DISALLOW_COPY_AND_ASSIGN(SyncBackupManager);
-};
-
-}  // namespace syncer
-
-#endif  // SYNC_INTERNAL_API_SYNC_BACKUP_MANAGER_H_
diff --git a/sync/internal_api/sync_backup_manager_unittest.cc b/sync/internal_api/sync_backup_manager_unittest.cc
deleted file mode 100644
index 919356d..0000000
--- a/sync/internal_api/sync_backup_manager_unittest.cc
+++ /dev/null
@@ -1,185 +0,0 @@
-// Copyright 2014 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "sync/internal_api/sync_backup_manager.h"
-
-#include <string>
-
-#include "base/files/scoped_temp_dir.h"
-#include "base/run_loop.h"
-#include "sync/internal_api/public/read_node.h"
-#include "sync/internal_api/public/read_transaction.h"
-#include "sync/internal_api/public/sessions/sync_session_snapshot.h"
-#include "sync/internal_api/public/test/test_internal_components_factory.h"
-#include "sync/internal_api/public/write_node.h"
-#include "sync/internal_api/public/write_transaction.h"
-#include "sync/syncable/entry.h"
-#include "sync/test/test_directory_backing_store.h"
-#include "testing/gmock/include/gmock/gmock.h"
-#include "testing/gtest/include/gtest/gtest.h"
-#include "url/gurl.h"
-
-using ::testing::_;
-using ::testing::Invoke;
-using ::testing::WithArgs;
-
-namespace syncer {
-
-namespace {
-
-void OnConfigDone(bool success) {
-  EXPECT_TRUE(success);
-}
-
-class SyncBackupManagerTest : public syncer::SyncManager::Observer,
-                              public testing::Test {
- public:
-  MOCK_METHOD1(OnSyncCycleCompleted,
-               void(const sessions::SyncSessionSnapshot&));
-  MOCK_METHOD1(OnConnectionStatusChange, void(ConnectionStatus));
-  MOCK_METHOD1(OnActionableError, void(const SyncProtocolError&));
-  MOCK_METHOD1(OnMigrationRequested, void(ModelTypeSet));
-  MOCK_METHOD1(OnProtocolEvent, void(const ProtocolEvent&));
-  MOCK_METHOD4(OnInitializationComplete,
-               void(const WeakHandle<JsBackend>&,
-                    const WeakHandle<DataTypeDebugInfoListener>&,
-                    bool, ModelTypeSet));
-
- protected:
-  void SetUp() override {
-    CHECK(temp_dir_.CreateUniqueTempDir());
-  }
-
-  void InitManager(SyncManager* manager,
-                   InternalComponentsFactory::StorageOption storage_option) {
-    manager_ = manager;
-    EXPECT_CALL(*this, OnInitializationComplete(_, _, _, _))
-        .WillOnce(WithArgs<2>(Invoke(this,
-                                     &SyncBackupManagerTest::HandleInit)));
-
-    manager->AddObserver(this);
-
-    base::RunLoop run_loop;
-
-    SyncManager::InitArgs args;
-    args.database_location = temp_dir_.path();
-    args.event_handler = MakeWeakHandle(base::WeakPtr<JsEventHandler>());
-    args.service_url = GURL("https://example.com/");
-    args.post_factory = scoped_ptr<HttpPostProviderFactory>();
-    args.internal_components_factory.reset(new TestInternalComponentsFactory(
-        InternalComponentsFactory::Switches(), storage_option,
-        &storage_used_));
-    manager->Init(&args);
-    EXPECT_EQ(InternalComponentsFactory::STORAGE_ON_DISK_DEFERRED,
-              storage_used_);
-    loop_.PostTask(FROM_HERE, run_loop.QuitClosure());
-    run_loop.Run();
-  }
-
-  void CreateEntry(UserShare* user_share, ModelType type,
-                   const std::string& client_tag) {
-    WriteTransaction trans(FROM_HERE, user_share);
-
-    WriteNode node(&trans);
-    EXPECT_EQ(WriteNode::INIT_SUCCESS,
-              node.InitUniqueByCreation(type, client_tag));
-  }
-
-  void ConfigureSyncer() {
-    manager_->ConfigureSyncer(CONFIGURE_REASON_NEW_CLIENT,
-                              ModelTypeSet(SEARCH_ENGINES),
-                              ModelTypeSet(), ModelTypeSet(), ModelTypeSet(),
-                              ModelSafeRoutingInfo(),
-                              base::Bind(&OnConfigDone, true),
-                              base::Bind(&OnConfigDone, false));
-  }
-
-  void HandleInit(bool success) {
-    if (success) {
-      loop_.PostTask(FROM_HERE,
-                     base::Bind(&SyncBackupManagerTest::ConfigureSyncer,
-                                base::Unretained(this)));
-    } else {
-      manager_->ShutdownOnSyncThread(STOP_SYNC);
-    }
-  }
-
-  base::ScopedTempDir temp_dir_;
-  base::MessageLoop loop_;    // Needed for WeakHandle
-  SyncManager* manager_;
-  InternalComponentsFactory::StorageOption storage_used_;
-};
-
-TEST_F(SyncBackupManagerTest, NormalizeEntry) {
-  scoped_ptr<SyncBackupManager> manager(new SyncBackupManager);
-  InitManager(manager.get(), InternalComponentsFactory::STORAGE_IN_MEMORY);
-
-  CreateEntry(manager->GetUserShare(), SEARCH_ENGINES, "test");
-
-  {
-    // New entry is local and unsynced at first.
-    ReadTransaction trans(FROM_HERE, manager->GetUserShare());
-    ReadNode pref(&trans);
-    EXPECT_EQ(BaseNode::INIT_OK,
-              pref.InitByClientTagLookup(SEARCH_ENGINES, "test"));
-    EXPECT_FALSE(pref.GetEntry()->GetId().ServerKnows());
-    EXPECT_TRUE(pref.GetEntry()->GetIsUnsynced());
-  }
-
-  manager->SaveChanges();
-
-  {
-    // New entry has server ID and unsynced bit is cleared after saving.
-    ReadTransaction trans(FROM_HERE, manager->GetUserShare());
-    ReadNode pref(&trans);
-    EXPECT_EQ(BaseNode::INIT_OK,
-              pref.InitByClientTagLookup(SEARCH_ENGINES, "test"));
-    EXPECT_TRUE(pref.GetEntry()->GetId().ServerKnows());
-    EXPECT_FALSE(pref.GetEntry()->GetIsUnsynced());
-  }
-}
-
-TEST_F(SyncBackupManagerTest, PersistWithSwitchToSyncShutdown) {
-  scoped_ptr<SyncBackupManager> manager(new SyncBackupManager);
-  InitManager(manager.get(),
-              InternalComponentsFactory::STORAGE_ON_DISK_DEFERRED);
-
-  CreateEntry(manager->GetUserShare(), SEARCH_ENGINES, "test");
-  manager->SaveChanges();
-  manager->ShutdownOnSyncThread(SWITCH_MODE_SYNC);
-
-  // Reopen db to verify entry is persisted.
-  manager.reset(new SyncBackupManager);
-  InitManager(manager.get(), InternalComponentsFactory::STORAGE_ON_DISK);
-  {
-    ReadTransaction trans(FROM_HERE, manager->GetUserShare());
-    ReadNode pref(&trans);
-    EXPECT_EQ(BaseNode::INIT_OK,
-              pref.InitByClientTagLookup(SEARCH_ENGINES, "test"));
-    EXPECT_TRUE(pref.GetEntry()->GetId().ServerKnows());
-    EXPECT_FALSE(pref.GetEntry()->GetIsUnsynced());
-  }
-}
-
-TEST_F(SyncBackupManagerTest, DontPersistWithOtherShutdown) {
-  scoped_ptr<SyncBackupManager> manager(new SyncBackupManager);
-  InitManager(manager.get(),
-              InternalComponentsFactory::STORAGE_ON_DISK_DEFERRED);
-
-  CreateEntry(manager->GetUserShare(), SEARCH_ENGINES, "test");
-  manager->SaveChanges();
-  manager->ShutdownOnSyncThread(STOP_SYNC);
-  EXPECT_FALSE(base::PathExists(
-      temp_dir_.path().Append(syncable::Directory::kSyncDatabaseFilename)));
-}
-
-TEST_F(SyncBackupManagerTest, FailToInitialize) {
-  // Test graceful shutdown on initialization failure.
-  scoped_ptr<SyncBackupManager> manager(new SyncBackupManager);
-  InitManager(manager.get(), InternalComponentsFactory::STORAGE_INVALID);
-}
-
-}  // anonymous namespace
-
-}  // namespace syncer
diff --git a/sync/internal_api/sync_manager_factory.cc b/sync/internal_api/sync_manager_factory.cc
index 288b5da..48ff69d 100644
--- a/sync/internal_api/sync_manager_factory.cc
+++ b/sync/internal_api/sync_manager_factory.cc
@@ -4,32 +4,18 @@
 
 #include "sync/internal_api/public/sync_manager_factory.h"
 
-#include "sync/internal_api/sync_backup_manager.h"
 #include "sync/internal_api/sync_manager_impl.h"
-#include "sync/internal_api/sync_rollback_manager.h"
 
 namespace syncer {
 
-SyncManagerFactory::SyncManagerFactory(SyncManagerFactory::MANAGER_TYPE type)
-    : type_(type) {
-}
+SyncManagerFactory::SyncManagerFactory() {}
 
 SyncManagerFactory::~SyncManagerFactory() {
 }
 
 scoped_ptr<SyncManager> SyncManagerFactory::CreateSyncManager(
     const std::string& name) {
-  switch (type_) {
-    case NORMAL:
-      return scoped_ptr<SyncManager>(new SyncManagerImpl(name));
-    case BACKUP:
-      return scoped_ptr<SyncManager>(new SyncBackupManager());
-    case ROLLBACK:
-      return scoped_ptr<SyncManager>(new SyncRollbackManager());
-    default:
-      NOTREACHED();
-      return scoped_ptr<SyncManager>(new SyncManagerImpl(name));
-  }
+  return scoped_ptr<SyncManager>(new SyncManagerImpl(name));
 }
 
 }  // namespace syncer
diff --git a/sync/internal_api/sync_rollback_manager.cc b/sync/internal_api/sync_rollback_manager.cc
deleted file mode 100644
index e2a5c84..0000000
--- a/sync/internal_api/sync_rollback_manager.cc
+++ /dev/null
@@ -1,128 +0,0 @@
-// Copyright 2014 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "sync/internal_api/sync_rollback_manager.h"
-
-#include <stddef.h>
-#include <stdint.h>
-
-#include "sync/internal_api/public/base/model_type.h"
-#include "sync/internal_api/public/read_node.h"
-#include "sync/internal_api/public/read_transaction.h"
-#include "sync/internal_api/public/util/syncer_error.h"
-#include "sync/internal_api/public/write_transaction.h"
-#include "sync/syncable/directory.h"
-#include "sync/syncable/mutable_entry.h"
-#include "url/gurl.h"
-
-namespace syncer {
-
-SyncRollbackManager::SyncRollbackManager()
-    : change_delegate_(NULL) {
-}
-
-SyncRollbackManager::~SyncRollbackManager() {
-}
-
-void SyncRollbackManager::Init(InitArgs* args) {
-  if (SyncRollbackManagerBase::InitInternal(
-          args->database_location,
-          args->internal_components_factory.get(),
-          InternalComponentsFactory::STORAGE_ON_DISK,
-          args->unrecoverable_error_handler,
-          args->report_unrecoverable_error_function)) {
-    change_delegate_ = args->change_delegate;
-
-    for (size_t i = 0; i < args->workers.size(); ++i) {
-      ModelSafeGroup group = args->workers[i]->GetModelSafeGroup();
-      CHECK(workers_.find(group) == workers_.end());
-      workers_[group] = args->workers[i];
-    }
-
-    rollback_ready_types_ = GetUserShare()->directory->InitialSyncEndedTypes();
-    rollback_ready_types_.RetainAll(BackupTypes());
-  }
-}
-
-void SyncRollbackManager::StartSyncingNormally(
-    const ModelSafeRoutingInfo& routing_info,
-    base::Time last_poll_time) {
-  if (rollback_ready_types_.Empty()) {
-    NotifyRollbackDone();
-    return;
-  }
-
-  std::map<ModelType, syncable::Directory::Metahandles> to_delete;
-  {
-    WriteTransaction trans(FROM_HERE, GetUserShare());
-    syncable::Directory::Metahandles unsynced;
-    GetUserShare()->directory->GetUnsyncedMetaHandles(trans.GetWrappedTrans(),
-                                                      &unsynced);
-    for (size_t i = 0; i < unsynced.size(); ++i) {
-      syncable::MutableEntry e(trans.GetWrappedWriteTrans(),
-                               syncable::GET_BY_HANDLE, unsynced[i]);
-      if (!e.good() || e.GetIsDel() || e.GetId().ServerKnows())
-        continue;
-
-      // TODO(haitaol): roll back entries that are backed up but whose content
-      //                is merged with local model during association.
-
-      ModelType type = GetModelTypeFromSpecifics(e.GetSpecifics());
-      if (!rollback_ready_types_.Has(type))
-        continue;
-
-      to_delete[type].push_back(unsynced[i]);
-    }
-  }
-
-  for (std::map<ModelType, syncable::Directory::Metahandles>::iterator it =
-      to_delete.begin(); it != to_delete.end(); ++it) {
-    ModelSafeGroup group = routing_info.find(it->first)->second;
-    CHECK(workers_.find(group) != workers_.end());
-    workers_[group]->DoWorkAndWaitUntilDone(
-        base::Bind(&SyncRollbackManager::DeleteOnWorkerThread,
-                   base::Unretained(this),
-                   it->first, it->second));
-  }
-
-  NotifyRollbackDone();
-}
-
-SyncerError SyncRollbackManager::DeleteOnWorkerThread(
-    ModelType type,
-    std::vector<int64_t> handles) {
-  CHECK(change_delegate_);
-
-  {
-    ChangeRecordList deletes;
-    WriteTransaction trans(FROM_HERE, GetUserShare());
-    for (size_t i = 0; i < handles.size(); ++i) {
-      syncable::MutableEntry e(trans.GetWrappedWriteTrans(),
-                               syncable::GET_BY_HANDLE, handles[i]);
-      if (!e.good() || e.GetIsDel())
-        continue;
-
-      ChangeRecord del;
-      del.action = ChangeRecord::ACTION_DELETE;
-      del.id = handles[i];
-      del.specifics = e.GetSpecifics();
-      deletes.push_back(del);
-    }
-
-    change_delegate_->OnChangesApplied(type, 1, &trans,
-                                       MakeImmutable(&deletes));
-  }
-
-  change_delegate_->OnChangesComplete(type);
-  return SYNCER_OK;
-}
-
-void SyncRollbackManager::NotifyRollbackDone() {
-  SyncProtocolError error;
-  error.action = ROLLBACK_DONE;
-  FOR_EACH_OBSERVER(SyncManager::Observer, *GetObservers(),
-                    OnActionableError(error));
-}
-
-}  // namespace syncer
diff --git a/sync/internal_api/sync_rollback_manager.h b/sync/internal_api/sync_rollback_manager.h
deleted file mode 100644
index d41086a..0000000
--- a/sync/internal_api/sync_rollback_manager.h
+++ /dev/null
@@ -1,52 +0,0 @@
-// Copyright 2014 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef SYNC_INTERNAL_API_SYNC_ROLLBACK_MANAGER_H_
-#define SYNC_INTERNAL_API_SYNC_ROLLBACK_MANAGER_H_
-
-#include <stdint.h>
-
-#include <map>
-#include <string>
-#include <vector>
-
-#include "base/macros.h"
-#include "sync/internal_api/sync_rollback_manager_base.h"
-
-class GURL;
-
-namespace syncer {
-
-// SyncRollbackManager restores user's data to pre-sync state using backup
-// DB created by SyncBackupManager.
-class SYNC_EXPORT SyncRollbackManager : public SyncRollbackManagerBase {
- public:
-  SyncRollbackManager();
-  ~SyncRollbackManager() override;
-
-  // SyncManager implementation.
-  void Init(InitArgs* args) override;
-  void StartSyncingNormally(const ModelSafeRoutingInfo& routing_info,
-                            base::Time last_poll_time) override;
-
- private:
-  // Deletes specified entries in local model.
-  SyncerError DeleteOnWorkerThread(ModelType type,
-                                   std::vector<int64_t> handles);
-
-  void NotifyRollbackDone();
-
-  std::map<ModelSafeGroup, scoped_refptr<ModelSafeWorker> > workers_;
-
-  SyncManager::ChangeDelegate* change_delegate_;
-
-  // Types that can be rolled back.
-  ModelTypeSet rollback_ready_types_;
-
-  DISALLOW_COPY_AND_ASSIGN(SyncRollbackManager);
-};
-
-}  // namespace syncer
-
-#endif  // SYNC_INTERNAL_API_SYNC_ROLLBACK_MANAGER_H_
diff --git a/sync/internal_api/sync_rollback_manager_base.cc b/sync/internal_api/sync_rollback_manager_base.cc
deleted file mode 100644
index d62f354..0000000
--- a/sync/internal_api/sync_rollback_manager_base.cc
+++ /dev/null
@@ -1,329 +0,0 @@
-// Copyright 2014 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "sync/internal_api/sync_rollback_manager_base.h"
-
-#include <stdint.h>
-
-#include "sync/internal_api/public/base/model_type.h"
-#include "sync/internal_api/public/read_node.h"
-#include "sync/internal_api/public/read_transaction.h"
-#include "sync/internal_api/public/write_transaction.h"
-#include "sync/syncable/directory_backing_store.h"
-#include "sync/syncable/mutable_entry.h"
-
-namespace {
-
-// Permanent bookmark folders as defined in bookmark_model_associator.cc.
-// No mobile bookmarks because they only exists with sync enabled.
-const char kBookmarkBarTag[] = "bookmark_bar";
-const char kOtherBookmarksTag[] = "other_bookmarks";
-
-class DummyEntryptionHandler : public syncer::SyncEncryptionHandler {
-  void AddObserver(Observer* observer) override {}
-  void RemoveObserver(Observer* observer) override {}
-  void Init() override {}
-  void SetEncryptionPassphrase(const std::string& passphrase,
-                               bool is_explicit) override {}
-  void SetDecryptionPassphrase(const std::string& passphrase) override {}
-  void EnableEncryptEverything() override {}
-  bool IsEncryptEverythingEnabled() const override { return false; }
-  syncer::PassphraseType GetPassphraseType() const override {
-    return syncer::KEYSTORE_PASSPHRASE;
-  }
-};
-
-}  // anonymous namespace
-
-namespace syncer {
-
-SyncRollbackManagerBase::SyncRollbackManagerBase()
-    : dummy_handler_(new DummyEntryptionHandler),
-      initialized_(false),
-      weak_ptr_factory_(this) {
-}
-
-SyncRollbackManagerBase::~SyncRollbackManagerBase() {
-}
-
-bool SyncRollbackManagerBase::InitInternal(
-    const base::FilePath& database_location,
-    InternalComponentsFactory* internal_components_factory,
-    InternalComponentsFactory::StorageOption storage,
-    const WeakHandle<UnrecoverableErrorHandler>& unrecoverable_error_handler,
-    const base::Closure& report_unrecoverable_error_function) {
-  unrecoverable_error_handler_ = unrecoverable_error_handler;
-  report_unrecoverable_error_function_ = report_unrecoverable_error_function;
-
-  if (!InitBackupDB(database_location, internal_components_factory, storage)) {
-    NotifyInitializationFailure();
-    return false;
-  }
-
-  initialized_ = true;
-  NotifyInitializationSuccess();
-  return true;
-}
-
-ModelTypeSet SyncRollbackManagerBase::InitialSyncEndedTypes() {
-  return share_.directory->InitialSyncEndedTypes();
-}
-
-ModelTypeSet SyncRollbackManagerBase::GetTypesWithEmptyProgressMarkerToken(
-      ModelTypeSet types) {
-  ModelTypeSet inited_types = share_.directory->InitialSyncEndedTypes();
-  types.RemoveAll(inited_types);
-  return types;
-}
-
-bool SyncRollbackManagerBase::PurgePartiallySyncedTypes() {
-  NOTREACHED();
-  return true;
-}
-
-void SyncRollbackManagerBase::UpdateCredentials(
-    const SyncCredentials& credentials) {
-}
-
-void SyncRollbackManagerBase::StartSyncingNormally(
-    const ModelSafeRoutingInfo& routing_info,
-    base::Time last_poll_time) {}
-
-void SyncRollbackManagerBase::ConfigureSyncer(
-      ConfigureReason reason,
-      ModelTypeSet to_download,
-      ModelTypeSet to_purge,
-      ModelTypeSet to_journal,
-      ModelTypeSet to_unapply,
-      const ModelSafeRoutingInfo& new_routing_info,
-      const base::Closure& ready_task,
-      const base::Closure& retry_task) {
-  for (ModelTypeSet::Iterator type = to_download.First();
-      type.Good(); type.Inc()) {
-    if (InitTypeRootNode(type.Get())) {
-      if (type.Get() == BOOKMARKS) {
-        InitBookmarkFolder(kBookmarkBarTag);
-        InitBookmarkFolder(kOtherBookmarksTag);
-      }
-    }
-  }
-
-  ready_task.Run();
-}
-
-void SyncRollbackManagerBase::SetInvalidatorEnabled(bool invalidator_enabled) {
-}
-
-void SyncRollbackManagerBase::OnIncomingInvalidation(
-    syncer::ModelType type,
-    scoped_ptr<InvalidationInterface> invalidation) {
-  NOTREACHED();
-}
-
-void SyncRollbackManagerBase::AddObserver(SyncManager::Observer* observer) {
-  observers_.AddObserver(observer);
-}
-
-void SyncRollbackManagerBase::RemoveObserver(SyncManager::Observer* observer) {
-  observers_.RemoveObserver(observer);
-}
-
-SyncStatus SyncRollbackManagerBase::GetDetailedStatus() const {
-  return SyncStatus();
-}
-
-void SyncRollbackManagerBase::SaveChanges() {
-}
-
-void SyncRollbackManagerBase::ShutdownOnSyncThread(ShutdownReason reason) {
-  if (initialized_) {
-    share_.directory.reset();
-    initialized_ = false;
-  }
-}
-
-UserShare* SyncRollbackManagerBase::GetUserShare() {
-  return &share_;
-}
-
-const std::string SyncRollbackManagerBase::cache_guid() {
-  return share_.directory->cache_guid();
-}
-
-bool SyncRollbackManagerBase::ReceivedExperiment(Experiments* experiments) {
-  return false;
-}
-
-bool SyncRollbackManagerBase::HasUnsyncedItems() {
-  ReadTransaction trans(FROM_HERE, &share_);
-  syncable::Directory::Metahandles unsynced;
-  share_.directory->GetUnsyncedMetaHandles(trans.GetWrappedTrans(), &unsynced);
-  return !unsynced.empty();
-}
-
-SyncEncryptionHandler* SyncRollbackManagerBase::GetEncryptionHandler() {
-  return dummy_handler_.get();
-}
-
-void SyncRollbackManagerBase::RefreshTypes(ModelTypeSet types) {
-}
-
-void SyncRollbackManagerBase::HandleTransactionCompleteChangeEvent(
-    ModelTypeSet models_with_changes) {
-}
-
-ModelTypeSet SyncRollbackManagerBase::HandleTransactionEndingChangeEvent(
-      const syncable::ImmutableWriteTransactionInfo& write_transaction_info,
-      syncable::BaseTransaction* trans) {
-  return ModelTypeSet();
-}
-
-void SyncRollbackManagerBase::HandleCalculateChangesChangeEventFromSyncApi(
-    const syncable::ImmutableWriteTransactionInfo& write_transaction_info,
-    syncable::BaseTransaction* trans,
-    std::vector<int64_t>* entries_changed) {}
-
-void SyncRollbackManagerBase::HandleCalculateChangesChangeEventFromSyncer(
-    const syncable::ImmutableWriteTransactionInfo& write_transaction_info,
-    syncable::BaseTransaction* trans,
-    std::vector<int64_t>* entries_changed) {}
-
-void SyncRollbackManagerBase::OnTransactionWrite(
-    const syncable::ImmutableWriteTransactionInfo& write_transaction_info,
-    ModelTypeSet models_with_changes) {
-}
-
-void SyncRollbackManagerBase::NotifyInitializationSuccess() {
-  FOR_EACH_OBSERVER(
-      SyncManager::Observer, observers_,
-      OnInitializationComplete(
-          MakeWeakHandle(base::WeakPtr<JsBackend>()),
-          MakeWeakHandle(base::WeakPtr<DataTypeDebugInfoListener>()),
-          true, InitialSyncEndedTypes()));
-}
-
-void SyncRollbackManagerBase::NotifyInitializationFailure() {
-  FOR_EACH_OBSERVER(
-      SyncManager::Observer, observers_,
-      OnInitializationComplete(
-          MakeWeakHandle(base::WeakPtr<JsBackend>()),
-          MakeWeakHandle(base::WeakPtr<DataTypeDebugInfoListener>()),
-          false, ModelTypeSet()));
-}
-
-syncer_v2::SyncContextProxy* SyncRollbackManagerBase::GetSyncContextProxy() {
-  return NULL;
-}
-
-ScopedVector<syncer::ProtocolEvent>
-SyncRollbackManagerBase::GetBufferedProtocolEvents() {
-  return ScopedVector<syncer::ProtocolEvent>();
-}
-
-scoped_ptr<base::ListValue> SyncRollbackManagerBase::GetAllNodesForType(
-    syncer::ModelType type) {
-  ReadTransaction trans(FROM_HERE, GetUserShare());
-  scoped_ptr<base::ListValue> nodes(
-      trans.GetDirectory()->GetNodeDetailsForType(trans.GetWrappedTrans(),
-                                                  type));
-  return nodes;
-}
-
-bool SyncRollbackManagerBase::InitBackupDB(
-    const base::FilePath& sync_folder,
-    InternalComponentsFactory* internal_components_factory,
-    InternalComponentsFactory::StorageOption storage) {
-  base::FilePath backup_db_path = sync_folder.Append(
-      syncable::Directory::kSyncDatabaseFilename);
-  scoped_ptr<syncable::DirectoryBackingStore> backing_store =
-      internal_components_factory->BuildDirectoryBackingStore(storage, "backup",
-                                                              backup_db_path);
-
-  DCHECK(backing_store.get());
-  share_.directory.reset(
-      new syncable::Directory(
-          backing_store.release(),
-          unrecoverable_error_handler_,
-          report_unrecoverable_error_function_,
-          NULL,
-          NULL));
-  return syncable::OPENED ==
-      share_.directory->Open(
-          "backup", this,
-          MakeWeakHandle(weak_ptr_factory_.GetWeakPtr()));
-}
-
-bool SyncRollbackManagerBase::InitTypeRootNode(ModelType type) {
-  WriteTransaction trans(FROM_HERE, &share_);
-  ReadNode root(&trans);
-  if (BaseNode::INIT_OK == root.InitTypeRoot(type))
-    return true;
-
-  syncable::MutableEntry entry(trans.GetWrappedWriteTrans(),
-                               syncable::CREATE_NEW_UPDATE_ITEM,
-                               syncable::Id::CreateFromServerId(
-                                   ModelTypeToString(type)));
-  if (!entry.good())
-    return false;
-
-  entry.PutParentId(syncable::Id::GetRoot());
-  entry.PutBaseVersion(1);
-  entry.PutUniqueServerTag(ModelTypeToRootTag(type));
-  entry.PutNonUniqueName(ModelTypeToString(type));
-  entry.PutIsDel(false);
-  entry.PutIsDir(true);
-
-  sync_pb::EntitySpecifics specifics;
-  AddDefaultFieldValue(type, &specifics);
-  entry.PutSpecifics(specifics);
-
-  return true;
-}
-
-void SyncRollbackManagerBase::InitBookmarkFolder(const std::string& folder) {
-  WriteTransaction trans(FROM_HERE, &share_);
-  syncable::Entry bookmark_root(trans.GetWrappedTrans(),
-                                syncable::GET_TYPE_ROOT,
-                                BOOKMARKS);
-  if (!bookmark_root.good())
-    return;
-
-  syncable::MutableEntry entry(trans.GetWrappedWriteTrans(),
-                               syncable::CREATE_NEW_UPDATE_ITEM,
-                               syncable::Id::CreateFromServerId(folder));
-  if (!entry.good())
-    return;
-
-  entry.PutParentId(bookmark_root.GetId());
-  entry.PutBaseVersion(1);
-  entry.PutUniqueServerTag(folder);
-  entry.PutNonUniqueName(folder);
-  entry.PutIsDel(false);
-  entry.PutIsDir(true);
-
-  sync_pb::EntitySpecifics specifics;
-  AddDefaultFieldValue(BOOKMARKS, &specifics);
-  entry.PutSpecifics(specifics);
-}
-
-base::ObserverList<SyncManager::Observer>*
-SyncRollbackManagerBase::GetObservers() {
-  return &observers_;
-}
-
-void SyncRollbackManagerBase::RegisterDirectoryTypeDebugInfoObserver(
-    syncer::TypeDebugInfoObserver* observer) {}
-
-void SyncRollbackManagerBase::UnregisterDirectoryTypeDebugInfoObserver(
-    syncer::TypeDebugInfoObserver* observer) {}
-
-bool SyncRollbackManagerBase::HasDirectoryTypeDebugInfoObserver(
-    syncer::TypeDebugInfoObserver* observer) { return false; }
-
-void SyncRollbackManagerBase::RequestEmitDebugInfo() {}
-
-void SyncRollbackManagerBase::ClearServerData(
-    const ClearServerDataCallback& callback) {}
-
-}  // namespace syncer
diff --git a/sync/internal_api/sync_rollback_manager_base.h b/sync/internal_api/sync_rollback_manager_base.h
deleted file mode 100644
index ad3ad62..0000000
--- a/sync/internal_api/sync_rollback_manager_base.h
+++ /dev/null
@@ -1,149 +0,0 @@
-// Copyright 2014 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef SYNC_INTERNAL_API_SYNC_ROLLBACK_MANAGER_BASE_H_
-#define SYNC_INTERNAL_API_SYNC_ROLLBACK_MANAGER_BASE_H_
-
-#include <stdint.h>
-
-#include <string>
-#include <vector>
-
-#include "base/macros.h"
-#include "sync/base/sync_export.h"
-#include "sync/internal_api/public/http_post_provider_factory.h"
-#include "sync/internal_api/public/internal_components_factory.h"
-#include "sync/internal_api/public/sync_manager.h"
-#include "sync/internal_api/public/user_share.h"
-#include "sync/syncable/directory_change_delegate.h"
-#include "sync/syncable/transaction_observer.h"
-
-namespace syncer {
-
-class WriteTransaction;
-
-// Base class of sync managers used for backup and rollback. Two major
-// functions are:
-//   * Init(): load backup DB into sync directory.
-//   * ConfigureSyncer(): initialize permanent sync nodes (root, bookmark
-//                        permanent folders) for configured type as needed.
-//
-// Most of other functions are no ops.
-class SYNC_EXPORT SyncRollbackManagerBase
-    : public SyncManager,
-      public syncable::DirectoryChangeDelegate,
-      public syncable::TransactionObserver {
- public:
-  SyncRollbackManagerBase();
-  ~SyncRollbackManagerBase() override;
-
-  // SyncManager implementation.
-  ModelTypeSet InitialSyncEndedTypes() override;
-  ModelTypeSet GetTypesWithEmptyProgressMarkerToken(
-      ModelTypeSet types) override;
-  bool PurgePartiallySyncedTypes() override;
-  void UpdateCredentials(const SyncCredentials& credentials) override;
-  void StartSyncingNormally(const ModelSafeRoutingInfo& routing_info,
-                            base::Time last_poll_time) override;
-  void ConfigureSyncer(ConfigureReason reason,
-                       ModelTypeSet to_download,
-                       ModelTypeSet to_purge,
-                       ModelTypeSet to_journal,
-                       ModelTypeSet to_unapply,
-                       const ModelSafeRoutingInfo& new_routing_info,
-                       const base::Closure& ready_task,
-                       const base::Closure& retry_task) override;
-  void SetInvalidatorEnabled(bool invalidator_enabled) override;
-  void OnIncomingInvalidation(
-      syncer::ModelType type,
-      scoped_ptr<InvalidationInterface> invalidation) override;
-  void AddObserver(SyncManager::Observer* observer) override;
-  void RemoveObserver(SyncManager::Observer* observer) override;
-  SyncStatus GetDetailedStatus() const override;
-  void SaveChanges() override;
-  void ShutdownOnSyncThread(ShutdownReason reason) override;
-  UserShare* GetUserShare() override;
-  const std::string cache_guid() override;
-  bool ReceivedExperiment(Experiments* experiments) override;
-  bool HasUnsyncedItems() override;
-  SyncEncryptionHandler* GetEncryptionHandler() override;
-  void RefreshTypes(ModelTypeSet types) override;
-  syncer_v2::SyncContextProxy* GetSyncContextProxy() override;
-  ScopedVector<ProtocolEvent> GetBufferedProtocolEvents() override;
-  scoped_ptr<base::ListValue> GetAllNodesForType(
-      syncer::ModelType type) override;
-  void ClearServerData(const ClearServerDataCallback& callback) override;
-
-  // DirectoryChangeDelegate implementation.
-  void HandleTransactionCompleteChangeEvent(
-      ModelTypeSet models_with_changes) override;
-  ModelTypeSet HandleTransactionEndingChangeEvent(
-      const syncable::ImmutableWriteTransactionInfo& write_transaction_info,
-      syncable::BaseTransaction* trans) override;
-  void HandleCalculateChangesChangeEventFromSyncApi(
-      const syncable::ImmutableWriteTransactionInfo& write_transaction_info,
-      syncable::BaseTransaction* trans,
-      std::vector<int64_t>* entries_changed) override;
-  void HandleCalculateChangesChangeEventFromSyncer(
-      const syncable::ImmutableWriteTransactionInfo& write_transaction_info,
-      syncable::BaseTransaction* trans,
-      std::vector<int64_t>* entries_changed) override;
-
-  // syncable::TransactionObserver implementation.
-  void OnTransactionWrite(
-      const syncable::ImmutableWriteTransactionInfo& write_transaction_info,
-      ModelTypeSet models_with_changes) override;
-
- protected:
-  base::ObserverList<SyncManager::Observer>* GetObservers();
-
-  // Initialize sync backup DB.
-  bool InitInternal(
-      const base::FilePath& database_location,
-      InternalComponentsFactory* internal_components_factory,
-      InternalComponentsFactory::StorageOption storage,
-      const WeakHandle<UnrecoverableErrorHandler>& unrecoverable_error_handler,
-      const base::Closure& report_unrecoverable_error_function);
-
-  void RegisterDirectoryTypeDebugInfoObserver(
-      syncer::TypeDebugInfoObserver* observer) override;
-  void UnregisterDirectoryTypeDebugInfoObserver(
-      syncer::TypeDebugInfoObserver* observer) override;
-  bool HasDirectoryTypeDebugInfoObserver(
-      syncer::TypeDebugInfoObserver* observer) override;
-  void RequestEmitDebugInfo() override;
-
-  bool initialized() const {
-    return initialized_;
-  }
-
- private:
-  void NotifyInitializationSuccess();
-  void NotifyInitializationFailure();
-
-  bool InitBackupDB(const base::FilePath& sync_folder,
-                    InternalComponentsFactory* internal_components_factory,
-                    InternalComponentsFactory::StorageOption storage);
-
-  bool InitTypeRootNode(ModelType type);
-  void InitBookmarkFolder(const std::string& folder);
-
-  UserShare share_;
-  base::ObserverList<SyncManager::Observer> observers_;
-
-  WeakHandle<UnrecoverableErrorHandler> unrecoverable_error_handler_;
-  base::Closure report_unrecoverable_error_function_;
-
-  scoped_ptr<SyncEncryptionHandler> dummy_handler_;
-
-  bool initialized_;
-
-  base::WeakPtrFactory<SyncRollbackManagerBase> weak_ptr_factory_;
-
-  DISALLOW_COPY_AND_ASSIGN(SyncRollbackManagerBase);
-};
-
-}  // namespace syncer
-
-#endif  // SYNC_INTERNAL_API_SYNC_ROLLBACK_MANAGER_BASE_H_
diff --git a/sync/internal_api/sync_rollback_manager_base_unittest.cc b/sync/internal_api/sync_rollback_manager_base_unittest.cc
deleted file mode 100644
index bb5ec93..0000000
--- a/sync/internal_api/sync_rollback_manager_base_unittest.cc
+++ /dev/null
@@ -1,84 +0,0 @@
-// Copyright 2014 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "sync/internal_api/sync_rollback_manager_base.h"
-
-#include "base/bind.h"
-#include "sync/internal_api/public/read_node.h"
-#include "sync/internal_api/public/read_transaction.h"
-#include "sync/internal_api/public/test/test_internal_components_factory.h"
-#include "testing/gtest/include/gtest/gtest.h"
-#include "url/gurl.h"
-
-namespace syncer {
-
-namespace {
-
-void OnConfigDone(bool success) {
-  EXPECT_TRUE(success);
-}
-
-class SyncTestRollbackManager : public SyncRollbackManagerBase {
- public:
-  void Init(InitArgs* args) override {
-    SyncRollbackManagerBase::InitInternal(
-        args->database_location,
-        args->internal_components_factory.get(),
-        InternalComponentsFactory::STORAGE_IN_MEMORY,
-        args->unrecoverable_error_handler,
-        args->report_unrecoverable_error_function);
-  }
-};
-
-class SyncRollbackManagerBaseTest : public testing::Test {
- protected:
-  void SetUp() override {
-    SyncManager::InitArgs args;
-    args.database_location = base::FilePath(base::FilePath::kCurrentDirectory);
-    args.service_url = GURL("https://example.com/");
-    args.internal_components_factory.reset(new TestInternalComponentsFactory(
-        InternalComponentsFactory::Switches(),
-        InternalComponentsFactory::STORAGE_IN_MEMORY,
-        &storage_used_));
-    manager_.Init(&args);
-    EXPECT_EQ(InternalComponentsFactory::STORAGE_IN_MEMORY, storage_used_);
-  }
-
-  SyncTestRollbackManager manager_;
-  base::MessageLoop loop_;    // Needed for WeakHandle
-  InternalComponentsFactory::StorageOption storage_used_;
-};
-
-TEST_F(SyncRollbackManagerBaseTest, InitTypeOnConfiguration) {
-  EXPECT_TRUE(manager_.InitialSyncEndedTypes().Empty());
-
-  manager_.ConfigureSyncer(
-      CONFIGURE_REASON_NEW_CLIENT,
-      ModelTypeSet(PREFERENCES, BOOKMARKS),
-      ModelTypeSet(), ModelTypeSet(), ModelTypeSet(), ModelSafeRoutingInfo(),
-      base::Bind(&OnConfigDone, true),
-      base::Bind(&OnConfigDone, false));
-
-  ReadTransaction trans(FROM_HERE, manager_.GetUserShare());
-  ReadNode pref_root(&trans);
-  EXPECT_EQ(BaseNode::INIT_OK,
-            pref_root.InitTypeRoot(PREFERENCES));
-
-  ReadNode bookmark_root(&trans);
-  EXPECT_EQ(BaseNode::INIT_OK,
-            bookmark_root.InitTypeRoot(BOOKMARKS));
-  ReadNode bookmark_bar(&trans);
-  EXPECT_EQ(BaseNode::INIT_OK,
-            bookmark_bar.InitByTagLookupForBookmarks("bookmark_bar"));
-  ReadNode bookmark_mobile(&trans);
-  EXPECT_EQ(BaseNode::INIT_FAILED_ENTRY_NOT_GOOD,
-            bookmark_mobile.InitByTagLookupForBookmarks("synced_bookmarks"));
-  ReadNode bookmark_other(&trans);
-  EXPECT_EQ(BaseNode::INIT_OK,
-            bookmark_other.InitByTagLookupForBookmarks("other_bookmarks"));
-}
-
-}  // anonymous namespace
-
-}  // namespace syncer
diff --git a/sync/internal_api/sync_rollback_manager_unittest.cc b/sync/internal_api/sync_rollback_manager_unittest.cc
deleted file mode 100644
index 400cebc..0000000
--- a/sync/internal_api/sync_rollback_manager_unittest.cc
+++ /dev/null
@@ -1,269 +0,0 @@
-// Copyright 2014 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "sync/internal_api/sync_rollback_manager.h"
-
-#include <stddef.h>
-#include <stdint.h>
-
-#include <set>
-
-#include "base/files/scoped_temp_dir.h"
-#include "base/run_loop.h"
-#include "sync/internal_api/public/read_node.h"
-#include "sync/internal_api/public/read_transaction.h"
-#include "sync/internal_api/public/sessions/sync_session_snapshot.h"
-#include "sync/internal_api/public/test/test_internal_components_factory.h"
-#include "sync/internal_api/public/write_node.h"
-#include "sync/internal_api/public/write_transaction.h"
-#include "sync/internal_api/sync_backup_manager.h"
-#include "sync/syncable/entry.h"
-#include "sync/test/engine/fake_model_worker.h"
-#include "sync/test/test_directory_backing_store.h"
-#include "testing/gmock/include/gmock/gmock.h"
-#include "testing/gtest/include/gtest/gtest.h"
-#include "url/gurl.h"
-
-using ::testing::_;
-using ::testing::DoDefault;
-using ::testing::Invoke;
-using ::testing::Truly;
-using ::testing::WithArgs;
-
-namespace syncer {
-
-namespace {
-
-class TestChangeDelegate : public SyncManager::ChangeDelegate {
- public:
-  TestChangeDelegate() {
-    ON_CALL(*this, OnChangesApplied(_, _, _, _))
-        .WillByDefault(
-            WithArgs<3>(Invoke(this,
-                               &TestChangeDelegate::VerifyDeletes)));
-  }
-
-  void add_expected_delete(int64_t v) { expected_deletes_.insert(v); }
-
-  MOCK_METHOD4(OnChangesApplied,
-               void(ModelType model_type,
-                    int64_t model_version,
-                    const BaseTransaction* trans,
-                    const ImmutableChangeRecordList& changes));
-  MOCK_METHOD1(OnChangesComplete, void(ModelType model_type));
-
- private:
-  void VerifyDeletes(const ImmutableChangeRecordList& changes) {
-    std::set<int64_t> deleted;
-    for (size_t i = 0; i < changes.Get().size(); ++i) {
-      const ChangeRecord& change = (changes.Get())[i];
-      EXPECT_EQ(ChangeRecord::ACTION_DELETE, change.action);
-      EXPECT_TRUE(deleted.find(change.id) == deleted.end());
-      deleted.insert(change.id);
-    }
-    EXPECT_TRUE(expected_deletes_ == deleted);
-  }
-
-  std::set<int64_t> expected_deletes_;
-};
-
-class SyncRollbackManagerTest : public testing::Test,
-                                public SyncManager::Observer {
- protected:
-  void SetUp() override {
-    CHECK(temp_dir_.CreateUniqueTempDir());
-
-    worker_ = new FakeModelWorker(GROUP_UI);
-  }
-
-  MOCK_METHOD1(OnSyncCycleCompleted,
-               void(const sessions::SyncSessionSnapshot&));
-  MOCK_METHOD1(OnConnectionStatusChange, void(ConnectionStatus));
-  MOCK_METHOD4(OnInitializationComplete,
-               void(const WeakHandle<JsBackend>&,
-                    const WeakHandle<DataTypeDebugInfoListener>&,
-                    bool, ModelTypeSet));
-  MOCK_METHOD1(OnActionableError, void(const SyncProtocolError&));
-  MOCK_METHOD1(OnMigrationRequested, void(ModelTypeSet));
-  MOCK_METHOD1(OnProtocolEvent, void(const ProtocolEvent&));
-
-  void OnConfigDone(bool success) {
-    EXPECT_TRUE(success);
-  }
-
-  int64_t CreateEntry(UserShare* user_share,
-                      ModelType type,
-                      const std::string& client_tag) {
-    WriteTransaction trans(FROM_HERE, user_share);
-    WriteNode node(&trans);
-    EXPECT_EQ(WriteNode::INIT_SUCCESS,
-              node.InitUniqueByCreation(type, client_tag));
-    return node.GetId();
-  }
-
-  void InitManager(SyncManager* manager, ModelTypeSet types,
-                   TestChangeDelegate* delegate,
-                   InternalComponentsFactory::StorageOption storage_option) {
-    manager_ = manager;
-    types_ = types;
-
-    EXPECT_CALL(*this, OnInitializationComplete(_, _, _, _))
-        .WillOnce(WithArgs<2>(Invoke(this,
-                                     &SyncRollbackManagerTest::HandleInit)));
-
-    manager->AddObserver(this);
-
-    base::RunLoop run_loop;
-    SyncManager::InitArgs args;
-    args.database_location = temp_dir_.path();
-    args.service_url = GURL("https://example.com/");
-    args.workers.push_back(worker_);
-    args.change_delegate = delegate;
-
-    InternalComponentsFactory::StorageOption storage_used;
-    args.internal_components_factory.reset(new TestInternalComponentsFactory(
-        InternalComponentsFactory::Switches(), storage_option, &storage_used));
-    manager->Init(&args);
-    EXPECT_EQ(storage_option, storage_used);
-    loop_.PostTask(FROM_HERE, run_loop.QuitClosure());
-    run_loop.Run();
-  }
-
-  // Create and persist an entry by unique tag in DB.
-  void PrepopulateDb(ModelType type, const std::string& client_tag) {
-    SyncBackupManager backup_manager;
-    TestChangeDelegate delegate;
-    InitManager(&backup_manager, ModelTypeSet(type), &delegate,
-                InternalComponentsFactory::STORAGE_ON_DISK_DEFERRED);
-    CreateEntry(backup_manager.GetUserShare(), type, client_tag);
-    backup_manager.ShutdownOnSyncThread(SWITCH_MODE_SYNC);
-  }
-
-  // Verify entry with |client_tag| exists in sync directory.
-  bool VerifyEntry(UserShare* user_share, ModelType type,
-                   const std::string& client_tag) {
-    ReadTransaction trans(FROM_HERE, user_share);
-    ReadNode node(&trans);
-    return BaseNode::INIT_OK == node.InitByClientTagLookup(type, client_tag);
-  }
-
- private:
-  void ConfigureSyncer() {
-    manager_->ConfigureSyncer(
-          CONFIGURE_REASON_NEW_CLIENT,
-          types_,
-          ModelTypeSet(), ModelTypeSet(), ModelTypeSet(),
-          ModelSafeRoutingInfo(),
-          base::Bind(&SyncRollbackManagerTest::OnConfigDone,
-                     base::Unretained(this), true),
-          base::Bind(&SyncRollbackManagerTest::OnConfigDone,
-                     base::Unretained(this), false));
-  }
-
-  void HandleInit(bool success) {
-    if (success) {
-      loop_.PostTask(FROM_HERE,
-                     base::Bind(&SyncRollbackManagerTest::ConfigureSyncer,
-                                base::Unretained(this)));
-    } else {
-      manager_->ShutdownOnSyncThread(STOP_SYNC);
-    }
-  }
-
-  base::ScopedTempDir temp_dir_;
-  scoped_refptr<ModelSafeWorker> worker_;
-  base::MessageLoop loop_;    // Needed for WeakHandle
-  SyncManager* manager_;
-  ModelTypeSet types_;
-};
-
-bool IsRollbackDoneAction(SyncProtocolError e) {
-  return e.action == syncer::ROLLBACK_DONE;
-}
-
-TEST_F(SyncRollbackManagerTest, RollbackBasic) {
-  PrepopulateDb(PREFERENCES, "pref1");
-
-  TestChangeDelegate delegate;
-  SyncRollbackManager rollback_manager;
-  InitManager(&rollback_manager, ModelTypeSet(PREFERENCES), &delegate,
-              InternalComponentsFactory::STORAGE_ON_DISK);
-
-  // Simulate a new entry added during type initialization.
-  int64_t new_pref_id =
-      CreateEntry(rollback_manager.GetUserShare(), PREFERENCES, "pref2");
-
-  delegate.add_expected_delete(new_pref_id);
-  EXPECT_CALL(delegate, OnChangesApplied(_, _, _, _))
-      .Times(1)
-      .WillOnce(DoDefault());
-  EXPECT_CALL(delegate, OnChangesComplete(_)).Times(1);
-  EXPECT_CALL(*this, OnActionableError(Truly(IsRollbackDoneAction))).Times(1);
-
-  ModelSafeRoutingInfo routing_info;
-  routing_info[PREFERENCES] = GROUP_UI;
-  rollback_manager.StartSyncingNormally(routing_info, base::Time());
-}
-
-TEST_F(SyncRollbackManagerTest, NoRollbackOfTypesNotBackedUp) {
-  PrepopulateDb(PREFERENCES, "pref1");
-
-  TestChangeDelegate delegate;
-  SyncRollbackManager rollback_manager;
-  InitManager(&rollback_manager, ModelTypeSet(PREFERENCES, APPS), &delegate,
-              InternalComponentsFactory::STORAGE_ON_DISK);
-
-  // Simulate new entry added during type initialization.
-  int64_t new_pref_id =
-      CreateEntry(rollback_manager.GetUserShare(), PREFERENCES, "pref2");
-  CreateEntry(rollback_manager.GetUserShare(), APPS, "app1");
-
-  delegate.add_expected_delete(new_pref_id);
-  EXPECT_CALL(delegate, OnChangesApplied(_, _, _, _))
-      .Times(1)
-      .WillOnce(DoDefault());
-  EXPECT_CALL(delegate, OnChangesComplete(_)).Times(1);
-
-  ModelSafeRoutingInfo routing_info;
-  routing_info[PREFERENCES] = GROUP_UI;
-  rollback_manager.StartSyncingNormally(routing_info, base::Time());
-
-  // APP entry is still valid.
-  EXPECT_TRUE(VerifyEntry(rollback_manager.GetUserShare(), APPS, "app1"));
-}
-
-TEST_F(SyncRollbackManagerTest, BackupDbNotChangedOnAbort) {
-  PrepopulateDb(PREFERENCES, "pref1");
-
-  TestChangeDelegate delegate;
-  scoped_ptr<SyncRollbackManager> rollback_manager(
-      new SyncRollbackManager);
-  InitManager(rollback_manager.get(), ModelTypeSet(PREFERENCES), &delegate,
-              InternalComponentsFactory::STORAGE_ON_DISK);
-
-  // Simulate a new entry added during type initialization.
-  CreateEntry(rollback_manager->GetUserShare(), PREFERENCES, "pref2");
-
-  // Manager was shut down before sync starts.
-  rollback_manager->ShutdownOnSyncThread(STOP_SYNC);
-
-  // Verify new entry was not persisted.
-  rollback_manager.reset(new SyncRollbackManager);
-  InitManager(rollback_manager.get(), ModelTypeSet(PREFERENCES), &delegate,
-              InternalComponentsFactory::STORAGE_ON_DISK);
-  EXPECT_FALSE(VerifyEntry(rollback_manager->GetUserShare(), PREFERENCES,
-                           "pref2"));
-}
-
-TEST_F(SyncRollbackManagerTest, OnInitializationFailure) {
-  // Test graceful shutdown on initialization failure.
-  scoped_ptr<SyncRollbackManager> rollback_manager(
-      new SyncRollbackManager);
-  InitManager(rollback_manager.get(), ModelTypeSet(PREFERENCES), NULL,
-              InternalComponentsFactory::STORAGE_ON_DISK);
-}
-
-}  // anonymous namespace
-
-}  // namespace syncer
diff --git a/sync/internal_api/test/sync_manager_factory_for_profile_sync_test.cc b/sync/internal_api/test/sync_manager_factory_for_profile_sync_test.cc
index ff72bcd..4c0689d 100644
--- a/sync/internal_api/test/sync_manager_factory_for_profile_sync_test.cc
+++ b/sync/internal_api/test/sync_manager_factory_for_profile_sync_test.cc
@@ -10,7 +10,7 @@ namespace syncer {
 
 SyncManagerFactoryForProfileSyncTest::SyncManagerFactoryForProfileSyncTest(
     base::Closure init_callback)
-  : SyncManagerFactory(SyncManagerFactory::NORMAL),
+  : SyncManagerFactory(),
     init_callback_(init_callback) {
 }
 
@@ -20,9 +20,7 @@ scoped_ptr<syncer::SyncManager>
 SyncManagerFactoryForProfileSyncTest::CreateSyncManager(
     const std::string& name) {
   return scoped_ptr<syncer::SyncManager>(
-      new SyncManagerForProfileSyncTest(
-          name,
-          init_callback_));
+      new SyncManagerForProfileSyncTest(name, init_callback_));
 }
 
 }  // namespace syncer
diff --git a/sync/internal_api/test/test_internal_components_factory.cc b/sync/internal_api/test/test_internal_components_factory.cc
index 1e26b4e..d6a72fa 100644
--- a/sync/internal_api/test/test_internal_components_factory.cc
+++ b/sync/internal_api/test/test_internal_components_factory.cc
@@ -5,7 +5,6 @@
 #include "sync/internal_api/public/test/test_internal_components_factory.h"
 
 #include "sync/sessions/sync_session_context.h"
-#include "sync/syncable/deferred_on_disk_directory_backing_store.h"
 #include "sync/syncable/in_memory_directory_backing_store.h"
 #include "sync/syncable/on_disk_directory_backing_store.h"
 #include "sync/syncable/invalid_directory_backing_store.h"
@@ -69,10 +68,6 @@ TestInternalComponentsFactory::BuildDirectoryBackingStore(
       return scoped_ptr<syncable::DirectoryBackingStore>(
           new syncable::OnDiskDirectoryBackingStore(dir_name,
                                                     backing_filepath));
-    case STORAGE_ON_DISK_DEFERRED:
-      return scoped_ptr<syncable::DirectoryBackingStore>(
-          new syncable::DeferredOnDiskDirectoryBackingStore(dir_name,
-                                                            backing_filepath));
     case STORAGE_INVALID:
       return scoped_ptr<syncable::DirectoryBackingStore>(
           new syncable::InvalidDirectoryBackingStore());
diff --git a/sync/protocol/device_info_specifics.proto b/sync/protocol/device_info_specifics.proto
index 99af88b..0103aa6 100644
--- a/sync/protocol/device_info_specifics.proto
+++ b/sync/protocol/device_info_specifics.proto
@@ -37,7 +37,8 @@ message DeviceInfoSpecifics {
 
   // Last time when pre-sync data on the device was saved. The device can be
   // restored to state back to this time. In millisecond since UNIX epoch.
-  optional int64 backup_timestamp = 6;
+  // DEPRECATED in M50.
+  optional int64 deprecated_backup_timestamp = 6 [deprecated=true];
 
   // Device_id that is stable until user signs out. This device_id is used for
   // annotating login scoped refresh token.
diff --git a/sync/protocol/proto_enum_conversions.cc b/sync/protocol/proto_enum_conversions.cc
index 0c6cf73..84a5b03 100644
--- a/sync/protocol/proto_enum_conversions.cc
+++ b/sync/protocol/proto_enum_conversions.cc
@@ -164,7 +164,7 @@ const char* GetErrorTypeString(sync_pb::SyncEnums::ErrorType error_type) {
     ENUM_CASE(sync_pb::SyncEnums, TRANSIENT_ERROR);
     ENUM_CASE(sync_pb::SyncEnums, MIGRATION_DONE);
     ENUM_CASE(sync_pb::SyncEnums, DISABLED_BY_ADMIN);
-    ENUM_CASE(sync_pb::SyncEnums, USER_ROLLBACK);
+    ENUM_CASE(sync_pb::SyncEnums, DEPRECATED_USER_ROLLBACK);
     ENUM_CASE(sync_pb::SyncEnums, PARTIAL_FAILURE);
     ENUM_CASE(sync_pb::SyncEnums, CLIENT_DATA_OBSOLETE);
     ENUM_CASE(sync_pb::SyncEnums, UNKNOWN);
diff --git a/sync/protocol/proto_value_conversions.cc b/sync/protocol/proto_value_conversions.cc
index 4fee4ee..327723c 100644
--- a/sync/protocol/proto_value_conversions.cc
+++ b/sync/protocol/proto_value_conversions.cc
@@ -80,10 +80,6 @@ scoped_ptr<base::ListValue> MakeRepeatedValue(const F& fields,
   return list;
 }
 
-base::string16 TimestampToString(int64_t tm) {
-  return base::TimeFormatShortDateAndTime(syncer::ProtoTimeToTime(tm));
-}
-
 }  // namespace
 
 // Helper macros to reduce the amount of boilerplate.
@@ -412,7 +408,6 @@ scoped_ptr<base::DictionaryValue> DeviceInfoSpecificsToValue(
   SET_ENUM(device_type, GetDeviceTypeString);
   SET_STR(sync_user_agent);
   SET_STR(chrome_version);
-  SET_TIME_STR(backup_timestamp);
   SET_STR(signin_scoped_device_id);
   return value;
 }
diff --git a/sync/protocol/sync_enums.proto b/sync/protocol/sync_enums.proto
index bdfb45e..0e18575 100644
--- a/sync/protocol/sync_enums.proto
+++ b/sync/protocol/sync_enums.proto
@@ -96,7 +96,7 @@ message SyncEnums {
                                 // a server.
     DISABLED_BY_ADMIN    = 10;  // An administrator disabled sync for this
                                 // domain.
-    USER_ROLLBACK        = 11;  // Client told to stop syncing and roll back.
+    DEPRECATED_USER_ROLLBACK        = 11;  // Deprecated in M50.
     PARTIAL_FAILURE      = 12;  // Return when client want to update several
                                 // data types, but some of them failed(e.g.
                                 // throttled).
diff --git a/sync/protocol/sync_protocol_error.cc b/sync/protocol/sync_protocol_error.cc
index 992f6ac..c82d32e 100644
--- a/sync/protocol/sync_protocol_error.cc
+++ b/sync/protocol/sync_protocol_error.cc
@@ -22,7 +22,6 @@ const char* GetSyncErrorTypeString(SyncProtocolErrorType type) {
     ENUM_CASE(MIGRATION_DONE);
     ENUM_CASE(INVALID_CREDENTIAL);
     ENUM_CASE(DISABLED_BY_ADMIN);
-    ENUM_CASE(USER_ROLLBACK);
     ENUM_CASE(PARTIAL_FAILURE);
     ENUM_CASE(CLIENT_DATA_OBSOLETE);
     ENUM_CASE(UNKNOWN_ERROR);
@@ -39,8 +38,6 @@ const char* GetClientActionString(ClientAction action) {
     ENUM_CASE(STOP_AND_RESTART_SYNC);
     ENUM_CASE(DISABLE_SYNC_ON_CLIENT);
     ENUM_CASE(STOP_SYNC_FOR_DISABLED_ACCOUNT);
-    ENUM_CASE(DISABLE_SYNC_AND_ROLLBACK);
-    ENUM_CASE(ROLLBACK_DONE);
     ENUM_CASE(RESET_LOCAL_SYNC_DATA);
     ENUM_CASE(UNKNOWN_ACTION);
   }
diff --git a/sync/protocol/sync_protocol_error.h b/sync/protocol/sync_protocol_error.h
index 38c5f18..7ba8d6c 100644
--- a/sync/protocol/sync_protocol_error.h
+++ b/sync/protocol/sync_protocol_error.h
@@ -38,9 +38,6 @@ enum SyncProtocolErrorType {
   // An administrator disabled sync for this domain.
   DISABLED_BY_ADMIN,
 
-  // Client told to stop syncing this device and roll back local data.
-  USER_ROLLBACK,
-
   // Some of servers are busy. Try later with busy servers.
   PARTIAL_FAILURE,
 
@@ -72,13 +69,6 @@ enum ClientAction {
   // settings page that account is disabled.
   STOP_SYNC_FOR_DISABLED_ACCOUNT,
 
-  // Disable sync and roll back local model to pre-sync state.
-  DISABLE_SYNC_AND_ROLLBACK,
-
-  // Generated by SyncRollbackManager to notify ProfileSyncService that
-  // rollback is finished.
-  ROLLBACK_DONE,
-
   // Generated in response to CLIENT_DATA_OBSOLETE error. ProfileSyncService
   // should stop sync engine, delete directory and restart sync engine.
   RESET_LOCAL_SYNC_DATA,
diff --git a/sync/sync.gyp b/sync/sync.gyp
index 9981376..f5303cb 100644
--- a/sync/sync.gyp
+++ b/sync/sync.gyp
@@ -350,8 +350,6 @@
         'internal_api/read_node.cc',
         'internal_api/read_transaction.cc',
         'internal_api/shared_model_type_processor.cc',
-        'internal_api/sync_backup_manager.cc',
-        'internal_api/sync_backup_manager.h',
         'internal_api/sync_context.cc',
         'internal_api/sync_context_proxy.cc',
         'internal_api/sync_context_proxy_impl.cc',
@@ -362,10 +360,6 @@
         'internal_api/sync_manager_factory.cc',
         'internal_api/sync_manager_impl.cc',
         'internal_api/sync_manager_impl.h',
-        'internal_api/sync_rollback_manager.cc',
-        'internal_api/sync_rollback_manager.h',
-        'internal_api/sync_rollback_manager_base.cc',
-        'internal_api/sync_rollback_manager_base.h',
         'internal_api/syncapi_internal.cc',
         'internal_api/syncapi_internal.h',
         'internal_api/syncapi_server_connection_manager.cc',
@@ -401,8 +395,6 @@
         'sessions/sync_session.h',
         'sessions/sync_session_context.cc',
         'sessions/sync_session_context.h',
-        'syncable/deferred_on_disk_directory_backing_store.cc',
-        'syncable/deferred_on_disk_directory_backing_store.h',
         'syncable/dir_open_result.h',
         'syncable/directory.cc',
         'syncable/directory.h',
diff --git a/sync/sync_tests.gypi b/sync/sync_tests.gypi
index 122641e..bacf837 100644
--- a/sync/sync_tests.gypi
+++ b/sync/sync_tests.gypi
@@ -321,12 +321,9 @@
         'internal_api/public/util/proto_value_ptr_unittest.cc',
         'internal_api/public/util/weak_handle_unittest.cc',
         'internal_api/shared_model_type_processor_unittest.cc',
-        'internal_api/sync_backup_manager_unittest.cc',
         'internal_api/sync_context_proxy_impl_unittest.cc',
         'internal_api/sync_encryption_handler_impl_unittest.cc',
         'internal_api/sync_manager_impl_unittest.cc',
-        'internal_api/sync_rollback_manager_base_unittest.cc',
-        'internal_api/sync_rollback_manager_unittest.cc',
         'internal_api/syncapi_server_connection_manager_unittest.cc',
         'js/js_event_details_unittest.cc',
         'js/sync_js_controller_unittest.cc',
@@ -335,7 +332,6 @@
         'sessions/model_type_registry_unittest.cc',
         'sessions/nudge_tracker_unittest.cc',
         'sessions/status_controller_unittest.cc',
-        'syncable/deferred_on_disk_directory_backing_store_unittest.cc',
         'syncable/directory_backing_store_unittest.cc',
         'syncable/directory_unittest.cc',
         'syncable/directory_unittest.h',
diff --git a/sync/syncable/deferred_on_disk_directory_backing_store.cc b/sync/syncable/deferred_on_disk_directory_backing_store.cc
deleted file mode 100644
index 5e960d2..0000000
--- a/sync/syncable/deferred_on_disk_directory_backing_store.cc
+++ /dev/null
@@ -1,72 +0,0 @@
-// Copyright 2014 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "sync/syncable/deferred_on_disk_directory_backing_store.h"
-
-#include "base/logging.h"
-#include "base/metrics/histogram.h"
-#include "base/stl_util.h"
-#include "sync/syncable/syncable-inl.h"
-
-namespace syncer {
-namespace syncable {
-
-DeferredOnDiskDirectoryBackingStore::DeferredOnDiskDirectoryBackingStore(
-    const std::string& dir_name,
-    const base::FilePath& backing_file_path)
-    : OnDiskDirectoryBackingStore(dir_name, backing_file_path),
-      created_on_disk_(false) {
-}
-
-DeferredOnDiskDirectoryBackingStore::~DeferredOnDiskDirectoryBackingStore() {}
-
-bool DeferredOnDiskDirectoryBackingStore::SaveChanges(
-    const Directory::SaveChangesSnapshot& snapshot) {
-  DCHECK(CalledOnValidThread());
-
-  // Back out early if there is nothing to save.
-  if (!snapshot.HasUnsavedMetahandleChanges()) {
-    return true;
-  }
-  if (!created_on_disk_ && !CreateOnDisk())
-    return false;
-  return OnDiskDirectoryBackingStore::SaveChanges(snapshot);
-}
-
-bool DeferredOnDiskDirectoryBackingStore::CreateOnDisk() {
-  DCHECK(CalledOnValidThread());
-  DCHECK(!created_on_disk_);
-  ResetAndCreateConnection();
-  if (!base::DeleteFile(backing_file_path(), false))
-    return false;
-  if (!Open(backing_file_path()) || !InitializeTables())
-    return false;
-  created_on_disk_ = true;
-  return true;
-}
-
-DirOpenResult DeferredOnDiskDirectoryBackingStore::Load(
-    Directory::MetahandlesMap* handles_map,
-    JournalIndex* delete_journals,
-    MetahandleSet* metahandles_to_purge,
-    Directory::KernelLoadInfo* kernel_load_info) {
-  DCHECK(CalledOnValidThread());
-  // Open an in-memory database at first to create initial sync data needed by
-  // Directory.
-  CHECK(!IsOpen());
-  if (!OpenInMemory())
-    return FAILED_OPEN_DATABASE;
-
-  if (!InitializeTables())
-    return FAILED_OPEN_DATABASE;
-  if (!LoadEntries(handles_map, metahandles_to_purge))
-    return FAILED_DATABASE_CORRUPT;
-  if (!LoadInfo(kernel_load_info))
-    return FAILED_DATABASE_CORRUPT;
-
-  return OPENED;
-}
-
-}  // namespace syncable
-}  // namespace syncer
diff --git a/sync/syncable/deferred_on_disk_directory_backing_store.h b/sync/syncable/deferred_on_disk_directory_backing_store.h
deleted file mode 100644
index 0531737..0000000
--- a/sync/syncable/deferred_on_disk_directory_backing_store.h
+++ /dev/null
@@ -1,49 +0,0 @@
-// Copyright 2014 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef SYNC_SYNCABLE_DEFERRED_ON_DISK_DIRECTORY_BACKING_STORE_H_
-#define SYNC_SYNCABLE_DEFERRED_ON_DISK_DIRECTORY_BACKING_STORE_H_
-
-#include <string>
-
-#include "base/files/file_path.h"
-#include "base/macros.h"
-#include "sync/base/sync_export.h"
-#include "sync/syncable/on_disk_directory_backing_store.h"
-
-namespace syncer {
-namespace syncable {
-
-// Store used for backing up user's data before first sync. It creates an
-// in-memory store first and switch to on-disk store if SaveChanges() is
-// called, which only happens when SyncBackupManager is shut down and a
-// syncing backend is to be created. Thus we guarantee that user data is not
-// persisted until user is actually going to sync.
-class SYNC_EXPORT DeferredOnDiskDirectoryBackingStore
-    : public OnDiskDirectoryBackingStore {
- public:
-  DeferredOnDiskDirectoryBackingStore(const std::string& dir_name,
-                                      const base::FilePath& backing_file_path);
-  ~DeferredOnDiskDirectoryBackingStore() override;
-  DirOpenResult Load(Directory::MetahandlesMap* handles_map,
-                     JournalIndex* delete_journals,
-                     MetahandleSet* metahandles_to_purge,
-                     Directory::KernelLoadInfo* kernel_load_info) override;
-  bool SaveChanges(const Directory::SaveChangesSnapshot& snapshot) override;
-
- private:
-  // Create an on-disk directory backing store. Returns true on success, false
-  // on error.
-  bool CreateOnDisk();
-
-  // Whether an on-disk directory backing store has been created.
-  bool created_on_disk_;
-
-  DISALLOW_COPY_AND_ASSIGN(DeferredOnDiskDirectoryBackingStore);
-};
-
-}  // namespace syncable
-}  // namespace syncer
-
-#endif  // SYNC_SYNCABLE_DEFERRED_ON_DISK_DIRECTORY_BACKING_STORE_H_
diff --git a/sync/syncable/deferred_on_disk_directory_backing_store_unittest.cc b/sync/syncable/deferred_on_disk_directory_backing_store_unittest.cc
deleted file mode 100644
index a62060a..0000000
--- a/sync/syncable/deferred_on_disk_directory_backing_store_unittest.cc
+++ /dev/null
@@ -1,117 +0,0 @@
-// Copyright 2014 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "base/files/scoped_temp_dir.h"
-#include "base/message_loop/message_loop.h"
-#include "base/stl_util.h"
-#include "sync/syncable/deferred_on_disk_directory_backing_store.h"
-#include "sync/syncable/directory.h"
-#include "sync/syncable/entry_kernel.h"
-#include "sync/syncable/on_disk_directory_backing_store.h"
-#include "sync/syncable/syncable_delete_journal.h"
-#include "testing/gtest/include/gtest/gtest.h"
-
-namespace syncer {
-namespace syncable {
-namespace {
-
-static const base::FilePath::CharType kSyncDataFolderName[] =
-    FILE_PATH_LITERAL("Sync Data");
-
-class DeferredOnDiskDirectoryBackingStoreTest : public testing::Test {
- protected:
-  void SetUp() override {
-    CHECK(temp_dir_.CreateUniqueTempDir());
-    db_path_ = temp_dir_.path().Append(kSyncDataFolderName);
-  }
-
-  void TearDown() override { STLDeleteValues(&handles_map_); }
-
-  base::MessageLoop message_loop_;
-  base::ScopedTempDir temp_dir_;
-  base::FilePath db_path_;
-  Directory::MetahandlesMap handles_map_;
-  JournalIndex delete_journals_;
-  MetahandleSet metahandles_to_purge_;
-  Directory::KernelLoadInfo kernel_load_info_;
-};
-
-// Test initialization of root entry when calling Load().
-TEST_F(DeferredOnDiskDirectoryBackingStoreTest, Load) {
-  DeferredOnDiskDirectoryBackingStore store("test", db_path_);
-  EXPECT_EQ(OPENED, store.Load(&handles_map_, &delete_journals_,
-                               &metahandles_to_purge_, &kernel_load_info_));
-  EXPECT_TRUE(delete_journals_.empty());
-  EXPECT_TRUE(metahandles_to_purge_.empty());
-  ASSERT_EQ(1u, handles_map_.size());   // root node
-  ASSERT_TRUE(handles_map_.count(1));
-  EntryKernel* root = handles_map_[1];
-  EXPECT_TRUE(root->ref(ID).IsRoot());
-  EXPECT_EQ(1, root->ref(META_HANDLE));
-  EXPECT_TRUE(root->ref(IS_DIR));
-}
-
-// Test on-disk DB is not created if SaveChanges() is not called.
-TEST_F(DeferredOnDiskDirectoryBackingStoreTest,
-       DontPersistIfSavingChangesNotCalled) {
-  {
-    // Open and close.
-    DeferredOnDiskDirectoryBackingStore store("test", db_path_);
-    EXPECT_EQ(OPENED, store.Load(&handles_map_, &delete_journals_,
-                                 &metahandles_to_purge_, &kernel_load_info_));
-  }
-
-  EXPECT_FALSE(base::PathExists(db_path_));
-}
-
-// Test on-disk DB is not created when there are no changes.
-TEST_F(DeferredOnDiskDirectoryBackingStoreTest,
-       DontPersistWhenSavingNoChanges) {
-  {
-    // Open and close.
-    DeferredOnDiskDirectoryBackingStore store("test", db_path_);
-    EXPECT_EQ(OPENED, store.Load(&handles_map_, &delete_journals_,
-                                 &metahandles_to_purge_, &kernel_load_info_));
-
-    Directory::SaveChangesSnapshot snapshot;
-    store.SaveChanges(snapshot);
-  }
-
-  EXPECT_FALSE(base::PathExists(db_path_));
-}
-
-// Test changes are persisted to disk when SaveChanges() is called.
-TEST_F(DeferredOnDiskDirectoryBackingStoreTest, PersistWhenSavingValidChanges) {
-  {
-    // Open and close.
-    DeferredOnDiskDirectoryBackingStore store("test", db_path_);
-    EXPECT_EQ(OPENED, store.Load(&handles_map_, &delete_journals_,
-                                 &metahandles_to_purge_, &kernel_load_info_));
-
-    Directory::SaveChangesSnapshot snapshot;
-    EntryKernel* entry = new EntryKernel();
-    entry->put(ID, Id::CreateFromClientString("test_entry"));
-    entry->put(META_HANDLE, 2);
-    entry->mark_dirty(NULL);
-    snapshot.dirty_metas.insert(entry);
-    store.SaveChanges(snapshot);
-  }
-
-  STLDeleteValues(&handles_map_);
-
-  ASSERT_TRUE(base::PathExists(db_path_));
-  OnDiskDirectoryBackingStore read_store("test", db_path_);
-  EXPECT_EQ(OPENED,
-            read_store.Load(&handles_map_, &delete_journals_,
-                            &metahandles_to_purge_, &kernel_load_info_));
-  ASSERT_EQ(2u, handles_map_.size());
-  ASSERT_TRUE(handles_map_.count(1));     // root node
-  ASSERT_TRUE(handles_map_.count(2));
-  EntryKernel* entry = handles_map_[2];
-  EXPECT_EQ(Id::CreateFromClientString("test_entry"), entry->ref(ID));
-}
-
-}  // namespace
-}  // namespace syncable
-}  // namespace syncer
diff --git a/sync/tools/sync_client.cc b/sync/tools/sync_client.cc
index deba666..36c7561 100644
--- a/sync/tools/sync_client.cc
+++ b/sync/tools/sync_client.cc
@@ -396,7 +396,7 @@ int SyncClientMain(int argc, char* argv[]) {
   workers.push_back(passive_model_safe_worker);
 
   // Set up sync manager.
-  SyncManagerFactory sync_manager_factory(SyncManagerFactory::NORMAL);
+  SyncManagerFactory sync_manager_factory;
   scoped_ptr<SyncManager> sync_manager =
       sync_manager_factory.CreateSyncManager("sync_client manager");
   LoggingJsEventHandler js_event_handler;
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index bf75c1d..96a48bc 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -50212,6 +50212,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 </histogram>
 
 <histogram name="Sync.FirstSyncDelayByBackup" units="ms">
+  <obsolete>
+    Backup logic has been removed since 02/2016.
+  </obsolete>
   <owner>haitaol@chromium.org</owner>
   <summary>First sync delay casued by backing up user data.</summary>
 </histogram>