Persist Directory to disk when the app is backgrounded.

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>
@@ skipping 771 matching lines @@
       BrowsingDataRemover::Observer* observer);
   void SetClearingBrowseringDataForTesting(base::Callback<
       void(BrowsingDataRemover::Observer*, Profile*, base::Time, base::Time)>
                                                c);
 
   // Return the base URL of the Sync Server.
   static GURL GetSyncServiceURL(const base::CommandLine& command_line);
 
   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.
+  void FlushDirectory() const;
+
  protected:
   // Helper to configure the priority data types.
   void ConfigurePriorityDataTypes();
 
   // Helper to install and configure a data type manager.
   void ConfigureDataTypeManager();
 
   // Shuts down the backend sync components.
   // |reason| dictates if syncing is being disabled or not, and whether
   // to claim ownership of sync thread from backend.
@@ skipping 357 matching lines @@
   BrowsingDataRemover::Observer* browsing_data_remover_observer_;
 
   DISALLOW_COPY_AND_ASSIGN(ProfileSyncService);
 };
 
 bool ShouldShowActionOnUI(
     const syncer::SyncProtocolError& error);
 
 
 #endif  // CHROME_BROWSER_SYNC_PROFILE_SYNC_SERVICE_H_