Revert of Let SyncBackupManager keep backup data in memory until shutdown. Only persist (patchset #3 of https://codereview.chromium.org/455023003/)

Reason for revert:
sync_unit_tests broke on Linux dbg bot.

http://build.chromium.org/p/chromium.linux/buildstatus?builder=Linux%20Tests%20%28dbg%29%282%29&number=48388

------------------------------------------------------------

[ RUN      ] SyncManagerTestWithMockScheduler.ReConfiguration

GMOCK WARNING:
Uninteresting mock function call - returning directly.
Function call: Start(0)
NOTE: You can safely ignore the above warning unless this call should not happen.  Do not suppress it by blindly adding an EXPECT_CALL() if you don't mean to enforce the call.  See http://code.google.com/p/googlemock/wiki/CookBook#Knowing_When_to_Expect for details.
Stack trace:
../../sync/internal_api/sync_manager_impl_unittest.cc:838: Failure
Value of: storage_used_
Actual: 2880154539
Expected: InternalComponentsFactory::STORAGE_ON_DISK
Which is: 1
[  FAILED  ] SyncManagerTestWithMockScheduler.ReConfiguration (34 ms)
[828/829] SyncManagerTestWithMockScheduler.ReConfiguration (34 ms)
[0814/160010:ERROR:kill_posix.cc(191)] Unable to terminate process group 6975: No such process
[ RUN      ] SyncManagerTestWithMockScheduler.BasicConfiguration

GMOCK WARNING:
Uninteresting mock function call - returning directly.
Function call: Start(0)
NOTE: You can safely ignore the above warning unless this call should not happen.  Do not suppress it by blindly adding an EXPECT_CALL() if you don't mean to enforce the call.  See http://code.google.com/p/googlemock/wiki/CookBook#Knowing_When_to_Expect for details.
Stack trace:
../../sync/internal_api/sync_manager_impl_unittest.cc:838: Failure
Value of: storage_used_
Actual: 2880154539
Expected: InternalComponentsFactory::STORAGE_ON_DISK
Which is: 1
[  FAILED  ] SyncManagerTestWithMockScheduler.BasicConfiguration (29 ms)
[829/829] SyncManagerTestWithMockScheduler.BasicConfiguration (29 ms)

Original issue's description:
> Let SyncBackupManager keep backup data in memory until shutdown. Only persist
> backup data to disk if shutdown is due to switching to sync.
> 
> BUG=362679
> 
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=289709

TBR=zea@chromium.org,haitaol@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=362679

Review URL: https://codereview.chromium.org/477813002

Cr-Commit-Position: refs/heads/master@{#289718}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@289718 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 0 insertions, 232 deletions

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 0367e5b..0000000
--- a/sync/syncable/deferred_on_disk_directory_backing_store.cc
+++ /dev/null
@@ -1,73 +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_filepath)
-    : DirectoryBackingStore(dir_name),
-      backing_filepath_(backing_filepath),
-      db_is_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.dirty_metas.empty() && snapshot.metahandles_to_purge.empty() &&
-      snapshot.delete_journals.empty() &&
-      snapshot.delete_journals_to_purge.empty()) {
-    return true;
-  }
-
-  if (!db_is_on_disk_) {
-    if (!base::DeleteFile(backing_filepath_, false))
-      return false;
-
-    // Reopen DB on disk.
-    db_.reset(new sql::Connection);
-    db_->set_exclusive_locking();
-    db_->set_page_size(4096);
-    if (!db_->Open(backing_filepath_) || !InitializeTables())
-      return false;
-
-    db_is_on_disk_ = true;
-  }
-
-  return DirectoryBackingStore::SaveChanges(snapshot);
-}
-
-DirOpenResult DeferredOnDiskDirectoryBackingStore::Load(
-    Directory::MetahandlesMap* handles_map,
-    JournalIndex* delete_journals,
-    Directory::KernelLoadInfo* kernel_load_info) {
-  // Open an in-memory database at first to create initial sync data needed by
-  // Directory.
-  CHECK(!db_->is_open());
-  if (!db_->OpenInMemory())
-    return FAILED_OPEN_DATABASE;
-
-  if (!InitializeTables())
-    return FAILED_OPEN_DATABASE;
-  if (!LoadEntries(handles_map))
-    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 9e6429a..0000000
--- a/sync/syncable/deferred_on_disk_directory_backing_store.h
+++ /dev/null
@@ -1,45 +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 "base/files/file_path.h"
-#include "sync/base/sync_export.h"
-#include "sync/syncable/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_PRIVATE DeferredOnDiskDirectoryBackingStore
-    : public DirectoryBackingStore {
- public:
-  DeferredOnDiskDirectoryBackingStore(const std::string& dir_name,
-                                      const base::FilePath& backing_filepath);
-  virtual ~DeferredOnDiskDirectoryBackingStore();
-  virtual DirOpenResult Load(
-      Directory::MetahandlesMap* handles_map,
-      JournalIndex* delete_journals,
-      Directory::KernelLoadInfo* kernel_load_info) OVERRIDE;
-  virtual bool SaveChanges(const Directory::SaveChangesSnapshot& snapshot)
-      OVERRIDE;
-
- private:
-  base::FilePath backing_filepath_;
-
-  // Whether current DB is on disk.
-  bool db_is_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 b1053b8..0000000
--- a/sync/syncable/deferred_on_disk_directory_backing_store_unittest.cc
+++ /dev/null
@@ -1,114 +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/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:
-  virtual void SetUp() OVERRIDE {
-    CHECK(temp_dir_.CreateUniqueTempDir());
-    db_path_ = temp_dir_.path().Append(kSyncDataFolderName);
-  }
-
-  virtual void TearDown() OVERRIDE {
-    STLDeleteValues(&handles_map_);
-  }
-
-  base::ScopedTempDir temp_dir_;
-  base::FilePath db_path_;
-  Directory::MetahandlesMap handles_map_;
-  JournalIndex delete_journals_;
-  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_,
-                               &kernel_load_info_));
-  EXPECT_TRUE(delete_journals_.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_,
-                                 &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_,
-                                 &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_,
-                                 &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_,
-                                    &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