Persist Directory to disk when the app is backgrounded.

chrome/browser/sync/glue/sync_backend_host_impl.h

 // Copyright 2013 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_GLUE_SYNC_BACKEND_HOST_IMPL_H_
 #define CHROME_BROWSER_SYNC_GLUE_SYNC_BACKEND_HOST_IMPL_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 109 matching lines @@
   virtual syncer::sessions::SyncSessionSnapshot
       GetLastSessionSnapshot() const OVERRIDE;
   virtual bool HasUnsyncedItems() const OVERRIDE;
   virtual bool IsNigoriEnabled() const OVERRIDE;
   virtual syncer::PassphraseType GetPassphraseType() const OVERRIDE;
   virtual base::Time GetExplicitPassphraseTime() const OVERRIDE;
   virtual bool IsCryptographerReady(
       const syncer::BaseTransaction* trans) const OVERRIDE;
   virtual void GetModelSafeRoutingInfo(
       syncer::ModelSafeRoutingInfo* out) const OVERRIDE;
+  virtual void FlushDirectory() const OVERRIDE;
   virtual void RequestBufferedProtocolEventsAndEnableForwarding() OVERRIDE;
   virtual void DisableProtocolEventForwarding() OVERRIDE;
   virtual void EnableDirectoryTypeDebugInfoForwarding() OVERRIDE;
   virtual void DisableDirectoryTypeDebugInfoForwarding() OVERRIDE;
   virtual void GetAllNodesForTypes(
       syncer::ModelTypeSet types,
       base::Callback<void(const std::vector<syncer::ModelType>&,
                           ScopedVector<base::ListValue>)> type) OVERRIDE;
   virtual base::MessageLoop* GetSyncLoopForTesting() OVERRIDE;
 
@@ skipping 221 matching lines @@
 
   base::WeakPtrFactory<SyncBackendHostImpl> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(SyncBackendHostImpl);
 };
 
 }  // namespace browser_sync
 
 #endif  // CHROME_BROWSER_SYNC_GLUE_SYNC_BACKEND_HOST_IMPL_H_