Add an API to Pause and Resume background offlining requests.

components/offline_pages/background/request_queue_in_memory_store.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_QUEUE_IN_MEMORY_STORE_H_
 #define COMPONENTS_OFFLINE_PAGES_BACKGROUND_REQUEST_QUEUE_IN_MEMORY_STORE_H_
 
 #include <stdint.h>
 
 #include <map>
 
 #include "base/macros.h"
 #include "components/offline_pages/background/request_queue_store.h"
+#include "components/offline_pages/background/save_page_request.h"
 
 namespace offline_pages {
 
-class SavePageRequest;
-
 // Interface for classes storing save page requests.
 class RequestQueueInMemoryStore : public RequestQueueStore {
  public:
   RequestQueueInMemoryStore();
   ~RequestQueueInMemoryStore() override;
 
   // RequestQueueStore implementaiton.
   void GetRequests(const GetRequestsCallback& callback) override;
   void AddOrUpdateRequest(const SavePageRequest& request,
                           const UpdateCallback& callback) override;
+
   // Remove requests by request ID.  In case the |request_ids| is empty, the
   // result will be true, but the count of deleted pages will be 0.
   void RemoveRequests(const std::vector<int64_t>& request_ids,
                       const RemoveCallback& callback) override;
 
+  // Set the state of associated requests to |new_state|.
+  void ChangeRequestsState(const std::vector<int64_t>& request_ids,
+                           const SavePageRequest::RequestState new_state,
+                           const UpdateCallback& callback) override;
+
   void Reset(const ResetCallback& callback) override;
 
  private:
   typedef std::map<int64_t, SavePageRequest> RequestsMap;
   RequestsMap requests_;
 
   DISALLOW_COPY_AND_ASSIGN(RequestQueueInMemoryStore);
 };
 
 }  // namespace offline_pages
 
 #endif  // COMPONENTS_OFFLINE_PAGES_BACKGROUND_REQUEST_QUEUE_IN_MEMORY_STORE_H_