Add UMA data for memory pressure warning received for sync

chrome/browser/sync/profile_sync_service.h

 // Copyright (c) 2012 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 CHROME_BROWSER_SYNC_PROFILE_SYNC_SERVICE_H_
 #define CHROME_BROWSER_SYNC_PROFILE_SYNC_SERVICE_H_
 
 #include <set>
 #include <string>
 #include <utility>
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/files/file_path.h"
 #include "base/gtest_prod_util.h"
 #include "base/location.h"
+#include "base/memory/memory_pressure_listener.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/scoped_vector.h"
 #include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
 #include "base/strings/string16.h"
 #include "base/time/time.h"
 #include "base/timer/timer.h"
 #include "chrome/browser/browsing_data/browsing_data_remover.h"
 #include "chrome/browser/sync/backend_unrecoverable_error_handler.h"
 #include "chrome/browser/sync/backup_rollback_controller.h"
@@ skipping 857 matching lines @@
   // 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;
 
+  // Called when the system is under memory pressure.
+  void OnMemoryPressure(
+      base::MemoryPressureListener::MemoryPressureLevel memory_pressure_level);
+
+  // Check if previous shutdown is crash or not.

[stanisc, 2015/05/15 20:31:04]

If there was a crash that means there wasn't a clean shutdown.
So perhaps rephrase this a bit to make it clearer.
Also explain result of the function. It returns void. Does it have any side
effect?

[Gang Wu, 2015/05/15 21:13:46]

Done.

+  void CheckPreviousShutdownMemoryWarning();
+
   // Factory used to create various dependent objects.
   scoped_ptr<ProfileSyncComponentsFactory> factory_;
 
   // The profile whose data we are synchronizing.
   Profile* profile_;
 
   // The class that handles getting, setting, and persisting sync
   // preferences.
   sync_driver::SyncPrefs sync_prefs_;
 
@@ skipping 159 matching lines @@
   // state is unknown. If time value is null, backup data doesn't exist.
   scoped_ptr<base::Time> last_backup_time_;
 
   BrowsingDataRemover::Observer* browsing_data_remover_observer_;
 
   // The full path to the sync data directory.
   base::FilePath directory_path_;
 
   scoped_ptr<browser_sync::SyncStoppedReporter> sync_stopped_reporter_;
 
+  // Listens for the system being under memory pressure.
+  scoped_ptr<base::MemoryPressureListener> memory_pressure_listener_;
+
   base::WeakPtrFactory<ProfileSyncService> weak_factory_;
 
   // We don't use |weak_factory_| for the StartupController because the weak
   // ptrs should be bound to the lifetime of ProfileSyncService and not to the
   // [Initialize -> sync disabled/shutdown] lifetime.  We don't pass
   // StartupController an Unretained reference to future-proof against
   // the controller impl changing to post tasks. Therefore, we have a separate
   // factory.
   base::WeakPtrFactory<ProfileSyncService> startup_controller_weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ProfileSyncService);
 };
 
 bool ShouldShowActionOnUI(
     const syncer::SyncProtocolError& error);
 
 
 #endif  // CHROME_BROWSER_SYNC_PROFILE_SYNC_SERVICE_H_