Don't start a second pre-render if one is in progress.

components/offline_pages/background/request_coordinator.h

 // 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.
 
 #ifndef COMPONENTS_OFFLINE_PAGES_BACKGROUND_REQUEST_COORDINATOR_H_
 #define COMPONENTS_OFFLINE_PAGES_BACKGROUND_REQUEST_COORDINATOR_H_
 
 #include <memory>
 
 #include "base/callback.h"
@@ skipping 78 matching lines @@
 
   // Called by the offliner when an offlining request is completed. (and by
   // tests).
   void OfflinerDoneCallback(const SavePageRequest& request,
                             Offliner::RequestStatus status);
 
   void TryNextRequest();
 
   friend class RequestCoordinatorTest;
 
+  bool request_in_progress_;

[chili, 2016/06/20 18:38:34]

though probably annoying to change - can we rename to is_request_in_progress_ to
more easily tell this is a boolean?  'request_in_progress' to me implies that
this is the actual request that is processing

[Pete Williamson, 2016/06/21 17:55:25]

renamed to is_busy_

   // RequestCoordinator takes over ownership of the policy
   std::unique_ptr<OfflinerPolicy> policy_;
   // OfflinerFactory.  Used to create offline pages. Owned.
   std::unique_ptr<OfflinerFactory> factory_;
   // RequestQueue.  Used to store incoming requests. Owned.
   std::unique_ptr<RequestQueue> queue_;
   // Scheduler. Used to request a callback when network is available.  Owned.
   std::unique_ptr<Scheduler> scheduler_;
   // Status of the most recent offlining.
   Offliner::RequestStatus last_offlining_status_;
   // Class to choose which request to schedule next
   std::unique_ptr<RequestPicker> picker_;
   // Calling this returns to the scheduler across the JNI bridge.
   base::Callback<void(bool)> scheduler_callback_;
   // Allows us to pass a weak pointer to callbacks.
   base::WeakPtrFactory<RequestCoordinator> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RequestCoordinator);
 };
 
 }  // namespace offline_pages
 
 #endif  // COMPONENTS_OFFLINE_PAGES_BACKGROUND_REQUEST_COORDINATOR_H_