Adds an observer for the request coordinator.

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 {
 
 // 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.
+  // Remove requests by request ID. The callback will get a list of
+  // UpdateMultipleRequestResults and a list of the removed requests (for use by
+  // notifications).
   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;
+  // Set the state of associated requests to |new_state|.  The callback will get
+  // a list of UpdateMultipleRequestResults, and a list of the updated requests.
+  void ChangeRequestsState(
+      const std::vector<int64_t>& request_ids,
+      const SavePageRequest::RequestState new_state,
+      const UpdateMultipleRequestsCallback& 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_