Add unit test for request coordiator

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 "base/callback.h"
 
 namespace offline_pages {
 
+class SavePageRequest;
+
 // Coordinates queueing and processing save page later requests.
 class RequestCoordinator {
  public:
   // Callback to report when the processing of a triggered task is complete.
   typedef base::Callback<void()> ProcessingDoneCallback;
 
-  struct SavePageRequest {
-    // TODO(dougarnett): define and consider making stand-alone.
-  };
-
   // TODO(dougarnett): How to inject Offliner factories and policy objects.
   RequestCoordinator();
 
   ~RequestCoordinator();
 
   // Queues |request| to later load and save when system conditions allow.
+  // Returns true if the page could be queued successfully.
   bool SavePageLater(const SavePageRequest& request);
 
   // Starts processing of one or more queued save page later requests.
   // Returns whether processing was started and that caller should expect
   // a callback. If processing was already active, returns false.
   bool StartProcessing(const ProcessingDoneCallback& callback);
 
   // Stops the current request processing if active. This is a way for
   // caller to abort processing; otherwise, processing will complete on
   // its own. In either case, the callback will be called when processing
   // is stopped or complete.
   void StopProcessing();
 
   // TODO(dougarnett): add policy support methods.
 };
 
 }  // namespace offline_pages
 
 #endif  // COMPONENTS_OFFLINE_PAGES_BACKGROUND_REQUEST_COORDINATOR_H_