Persist Directory to disk when the app is backgrounded.

chrome/browser/sync/profile_sync_service_android.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_PROFILE_SYNC_SERVICE_ANDROID_H_
 #define CHROME_BROWSER_SYNC_PROFILE_SYNC_SERVICE_ANDROID_H_
 
 #include <jni.h>
 #include <map>
 
@@ skipping 42 matching lines @@
 
   // Called from Java when the user manually disables sync
   void DisableSync(JNIEnv* env, jobject obj);
 
   // Called from Java when the user signs in to Chrome. Starts up sync.
   void SignInSync(JNIEnv* env, jobject obj);
 
   // Called from Java when the user signs out of Chrome
   void SignOutSync(JNIEnv* env, jobject obj);
 
+  // Called from Java when we get a signal that the Directory should be saved.
+  void FlushDirectory(JNIEnv* env, jobject obj);
+
   // Returns a string version of browser_sync::SyncBackendHost::StatusSummary
   base::android::ScopedJavaLocalRef<jstring> QuerySyncStatusSummary(
       JNIEnv* env, jobject obj);
 
   // Called from Java early during startup to ensure we use the correct
   // unique machine tag in session sync. Returns true if the machine tag was
   // succesfully set.
   // This must be called before the |SessionModelAssociator| is initialized.
   jboolean SetSyncSessionsId(JNIEnv* env, jobject obj, jstring tag);
 
@@ skipping 171 matching lines @@
 
   // The invalidation API spec allows for the possibility of redundant
   // invalidations, so keep track of the max versions and drop
   // invalidations with old versions.
   ObjectIdVersionMap max_invalidation_versions_;
 
   DISALLOW_COPY_AND_ASSIGN(ProfileSyncServiceAndroid);
 };
 
 #endif  // CHROME_BROWSER_SYNC_PROFILE_SYNC_SERVICE_ANDROID_H_