Make AttachmentServiceImpl clear backoff when reconnected to network.

sync/internal_api/public/attachments/task_queue.h

 // Copyright 2014 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 SYNC_INTERNAL_API_PUBLIC_ATTACHMENTS_TASK_QUEUE_H_
 #define SYNC_INTERNAL_API_PUBLIC_ATTACHMENTS_TASK_QUEUE_H_
 
 #include <deque>
 #include <set>
 
@@ skipping 104 matching lines @@
 
   // Cancel |task|.
   //
   // |task| is removed from the queue and will not be retried.  Does not affect
   // the backoff delay.
   //
   // May only be called after the HandleTaskCallback has been invoked with
   // |task|.
   void Cancel(const T& task);
 
- private:
-  FRIEND_TEST_ALL_PREFIXES(TaskQueueTest, Retry);
+  // Reset any backoff delay and resume dispatching of tasks.
+  //
+  // Useful for when you know the cause of previous failures has been resolved
+  // and you want don't want to wait for the accumulated backoff delay to
+  // elapse.
+  void ResetBackoff();
 
   // Use |timer| for scheduled events.
   //
   // Used in tests.  See also MockTimer.
   void SetTimerForTest(scoped_ptr<base::Timer> timer);
+
+ private:
   void FinishTask(const T& task);
   void ScheduleDispatch();
   void Dispatch();
   // Return true if we should dispatch tasks.
   bool ShouldDispatch();
 
   const HandleTaskCallback process_callback_;
   net::BackoffEntry::Policy backoff_policy_;
   scoped_ptr<net::BackoffEntry> backoff_entry_;
   // The number of tasks currently being handled.
@@ skipping 69 matching lines @@
 }
 
 template <typename T>
 void TaskQueue<T>::Cancel(const T& task) {
   DCHECK(CalledOnValidThread());
   FinishTask(task);
   ScheduleDispatch();
 }
 
 template <typename T>
+void TaskQueue<T>::ResetBackoff() {
+  backoff_timer_->Stop();
+  backoff_entry_->Reset();
+  ScheduleDispatch();
+}
+
+template <typename T>
 void TaskQueue<T>::SetTimerForTest(scoped_ptr<base::Timer> timer) {
   DCHECK(CalledOnValidThread());
   DCHECK(timer.get());
   backoff_timer_ = timer.Pass();
 }
 
 template <typename T>
 void TaskQueue<T>::FinishTask(const T& task) {
   DCHECK(CalledOnValidThread());
   DCHECK_GE(num_in_progress_, 1);
@@ skipping 30 matching lines @@
 }
 
 template <typename T>
 bool TaskQueue<T>::ShouldDispatch() {
   return num_in_progress_ < kMaxConcurrentTasks && !queue_.empty();
 }
 
 }  // namespace syncer
 
 #endif  //  SYNC_INTERNAL_API_PUBLIC_ATTACHMENTS_TASK_QUEUE_H_