[SyncFS] Add idle callback to SyncFileSystemService for testing

chrome/browser/sync_file_system/sync_process_runner.h

Index: chrome/browser/sync_file_system/sync_process_runner.h
diff --git a/chrome/browser/sync_file_system/sync_process_runner.h b/chrome/browser/sync_file_system/sync_process_runner.h
index 3fa10920fb3456bfed98b5f283ac91363535de57..118ca70917e89177ecc92ff85f804e586209847a 100644
--- a/chrome/browser/sync_file_system/sync_process_runner.h
+++ b/chrome/browser/sync_file_system/sync_process_runner.h
@@ -78,14 +78,14 @@ class SyncProcessRunner {
 
   int64 pending_changes() const { return pending_changes_; }
 
- protected:
-  void OnChangesUpdated(int64 pending_changes);
-  SyncFileSystemService* GetSyncService();
-
   // Returns the current service state.  Default implementation returns
   // sync_service()->GetSyncServiceState().
   virtual SyncServiceState GetServiceState();
 
+ protected:
+  void OnChangesUpdated(int64 pending_changes);
+  SyncFileSystemService* GetSyncService();
+
  private:
   void Finished(const base::TimeTicks& start_time, SyncStatusCode status);
   void Run();
@@ -99,6 +99,8 @@ class SyncProcessRunner {
   void ResetOldThrottling();
   void ResetThrottling();
 
+  void CheckIfIdle();
+
   std::string name_;
   Client* client_;
   size_t max_parallel_task_;