Add a general purpose facility for letting background tasks wait until

components/offline_pages/background/request_coordinator.cc

 // Copyright 2016 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.
 
 #include "components/offline_pages/background/request_coordinator.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/callback.h"
@@ skipping 56 matching lines @@
   Scheduler::TriggerCondition conditions;
   scheduler_->Schedule(conditions);
 }
 
 // Called in response to updating a request in the request queue.
 void RequestCoordinator::UpdateRequestCallback(
     RequestQueue::UpdateRequestResult result) {}
 
 // Called by the request picker when a request has been picked.
 void RequestCoordinator::RequestPicked(const SavePageRequest& request) {
-  Scheduler::TriggerCondition conditions;
-
-  // Ensure that the scheduler has actively scheduled a task.
-  scheduler_->Schedule(conditions);
-
   // Send the request on to the offliner.
   SendRequestToOffliner(request);
 }
 
 void RequestCoordinator::RequestQueueEmpty() {
   // Clear the outstanding "safety" task in the scheduler.
   scheduler_->Unschedule();
   // Return control to the scheduler when there is no more to do.
   scheduler_callback_.Run(true);
 }
@@ skipping 54 matching lines @@
     queue_->RemoveRequest(request.request_id(),
                           base::Bind(&RequestCoordinator::UpdateRequestCallback,
                                      weak_ptr_factory_.GetWeakPtr()));
   }
 
   // TODO(petewil): Check time budget. Return to the scheduler if we are out.
 
 
   // Start a request if we have time.
   TryNextRequest();
-
 }
 
 }  // namespace offline_pages