Persist Directory to disk when the app is backgrounded.

chrome/browser/sync/profile_sync_service_android.h

Index: chrome/browser/sync/profile_sync_service_android.h
diff --git a/chrome/browser/sync/profile_sync_service_android.h b/chrome/browser/sync/profile_sync_service_android.h
index 993b19287580d311b1dc04dc91a8d9f8d3951753..ed91465b92b5a66e04a656292c5290eb03f7370c 100644
--- a/chrome/browser/sync/profile_sync_service_android.h
+++ b/chrome/browser/sync/profile_sync_service_android.h
@@ -46,6 +46,9 @@ class ProfileSyncServiceAndroid : public ProfileSyncServiceObserver {
   // 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);