Revert of Convert enable_pre_sync_backup flag to new flags system. (patchset #2 id:20001 of https://codereview.chromium.org/1487873003/ )

Reason for revert:
Speculative revert, CrOS compile broken, more info on the bug.
BUG=563927

Original issue's description:
> Convert enable_pre_sync_backup flag to new flags system.
>
> This flag's usage is very isolated so is a good candidate for the new system. There is now a generated header for the #define rather than a global define.
>
> Reland of http://crrev.com/1478623004#ps60001
> TBR=zea@chromium.org
>
> Committed: https://crrev.com/db7f9756dc6e236589b90c76d6fa0f1244601e78
> Cr-Commit-Position: refs/heads/master@{#362365}

TBR=zea@chromium.org,brettw@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Review URL: https://codereview.chromium.org/1490713002

Cr-Commit-Position: refs/heads/master@{#362368}

7 files changed, 7 insertions, 46 deletions

diff --git a/components/browser_sync.gypi b/components/browser_sync.gypi
index 6abdffd..03393c7 100644
--- a/components/browser_sync.gypi
+++ b/components/browser_sync.gypi
@@ -30,7 +30,6 @@
         'syncable_prefs',
         'sync_bookmarks',
         'sync_driver',
-        'sync_driver_features',
         'sync_sessions',
         'variations',
         'version_info',
diff --git a/components/browser_sync/browser/profile_sync_service.cc b/components/browser_sync/browser/profile_sync_service.cc
index 04cb904..4ace523 100644
--- a/components/browser_sync/browser/profile_sync_service.cc
+++ b/components/browser_sync/browser/profile_sync_service.cc
@@ -49,7 +49,6 @@
 #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"
@@ -339,7 +338,7 @@ void ProfileSyncService::Initialize() {
     need_backup_ = false;
   }
 
-#if BUILDFLAG(ENABLE_PRE_SYNC_BACKUP)
+#if defined(ENABLE_PRE_SYNC_BACKUP)
   if (!running_rollback && !IsSignedIn()) {
     CleanUpBackup();
   }
@@ -2567,7 +2566,7 @@ void ProfileSyncService::ClearBrowsingDataSinceFirstSync() {
 void ProfileSyncService::CheckSyncBackupIfNeeded() {
   DCHECK_EQ(backend_mode_, SYNC);
 
-#if BUILDFLAG(ENABLE_PRE_SYNC_BACKUP)
+#if defined(ENABLE_PRE_SYNC_BACKUP)
   const base::Time last_synced_time = sync_prefs_.GetLastSyncedTime();
   // Check backup once a day.
   if (!last_backup_time_ &&
diff --git a/components/components_tests.gyp b/components/components_tests.gyp
index bf7b8d9..2a08ccee 100644
--- a/components/components_tests.gyp
+++ b/components/components_tests.gyp
@@ -1050,7 +1050,6 @@
         'components.gyp:ssl_errors',
         'components.gyp:suggestions',
         'components.gyp:sync_bookmarks',
-        '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 fa4aeb3..7bda955 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',
       ],
       'include_dirs': [
@@ -153,26 +152,6 @@
       ],
     },
     {
-      # 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 38b89a8..ffe41b8 100644
--- a/components/sync_driver/BUILD.gn
+++ b/components/sync_driver/BUILD.gn
@@ -2,7 +2,6 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-import("//build/buildflag_header.gni")
 import("//build/config/features.gni")
 
 source_set("sync_driver") {
@@ -121,9 +120,6 @@ source_set("sync_driver") {
     "user_selectable_sync_type.h",
   ]
 
-  public_deps = [
-    ":features",
-  ]
   deps = [
     "//base",
     "//base:prefs",
@@ -254,12 +250,3 @@ 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
index 3629973..b33bd60 100644
--- a/components/sync_driver/backup_rollback_controller.cc
+++ b/components/sync_driver/backup_rollback_controller.cc
@@ -12,13 +12,12 @@
 #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)
+#if defined(ENABLE_PRE_SYNC_BACKUP)
 // Number of rollback attempts to try before giving up.
 static const int kRollbackLimits = 3;
 
@@ -72,20 +71,20 @@ bool BackupRollbackController::StartRollback() {
 }
 
 void BackupRollbackController::OnRollbackReceived() {
-#if BUILDFLAG(ENABLE_PRE_SYNC_BACKUP)
+#if defined(ENABLE_PRE_SYNC_BACKUP)
   sync_prefs_->SetRemainingRollbackTries(kRollbackLimits);
 #endif
 }
 
 void BackupRollbackController::OnRollbackDone() {
-#if BUILDFLAG(ENABLE_PRE_SYNC_BACKUP)
+#if defined(ENABLE_PRE_SYNC_BACKUP)
   sync_prefs_->SetRemainingRollbackTries(0);
 #endif
 }
 
 // static
 bool BackupRollbackController::IsBackupEnabled() {
-#if BUILDFLAG(ENABLE_PRE_SYNC_BACKUP)
+#if defined(ENABLE_PRE_SYNC_BACKUP)
   const std::string group_name =
       base::FieldTrialList::FindFullName(kSyncBackupFinchName);
 
diff --git a/components/sync_driver/backup_rollback_controller_unittest.cc b/components/sync_driver/backup_rollback_controller_unittest.cc
index 7d5f9b6..9b94f21 100644
--- a/components/sync_driver/backup_rollback_controller_unittest.cc
+++ b/components/sync_driver/backup_rollback_controller_unittest.cc
@@ -12,7 +12,6 @@
 #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"
@@ -22,7 +21,7 @@ using ::testing::Return;
 
 namespace {
 
-#if BUILDFLAG(ENABLE_PRE_SYNC_BACKUP)
+#if defined(ENABLE_PRE_SYNC_BACKUP)
 
 class MockSigninManagerWrapper : public SigninManagerWrapper {
  public: