[SyncFS] Refine SyncProcessRunner's throttling algorithm for parallel task support

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 0143cfefd3bc556b869dacd85f2b991d74f916ee..c84a385124bb87397cfa4480bba9a8aa9d42eef5 100644
--- a/chrome/browser/sync_file_system/sync_process_runner.h
+++ b/chrome/browser/sync_file_system/sync_process_runner.h
@@ -75,7 +75,6 @@ class SyncProcessRunner {
 
   // Schedules a new sync.
   void Schedule();
-  void ScheduleIfNotRunning();
 
   int64 pending_changes() const { return pending_changes_; }
 
@@ -88,16 +87,29 @@ class SyncProcessRunner {
   virtual SyncServiceState GetServiceState();
 
  private:
-  void Finished(const base::TimeTicks& start_time, SyncStatusCode status);
+  void Finished(const base::TimeTicks& start_time,
+                SyncStatusCode status);
   void Run();
   void ScheduleInternal(int64 delay);
 
+  // Throttles new sync for |base_delay| milliseconds for an error case.
+  // If new sync is already throttled, back off the duration.
+  void ThrottleSync(int64 base_delay);
+
+  // Clears old throttling setting that is already over.
+  void ResetOldThrottling();
+  void ResetThrottling();
+
   std::string name_;
   Client* client_;
   int max_parallel_task_;
   int running_tasks_;
   scoped_ptr<TimerHelper> timer_helper_;
   base::TimeTicks last_scheduled_;
+
+  base::TimeTicks throttle_from_;
+  base::TimeTicks throttle_until_;
+
   int64 current_delay_;
   int64 last_delay_;
   int64 pending_changes_;