[Offline pages] Applying StoreState to track RequestQueueStore state

components/offline_pages/background/request_queue_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_STORE_H_
 #define COMPONENTS_OFFLINE_PAGES_BACKGROUND_REQUEST_QUEUE_STORE_H_
 
 #include <stdint.h>
 #include <vector>
 
@@ skipping 56 matching lines @@
 
   // Asynchronously changes the state of requests from the store using their
   // request id.
   virtual void ChangeRequestsState(
       const std::vector<int64_t>& request_ids,
       const SavePageRequest::RequestState new_state,
       const UpdateMultipleRequestsCallback& callback) = 0;
 
   // Resets the store.
   virtual void Reset(const ResetCallback& callback) = 0;
+
+  // Gets the store state.
+  virtual StoreState state() const = 0;
 };
 
 }  // namespace offline_pages
 
 #endif  // COMPONENTS_OFFLINE_PAGES_BACKGROUND_REQUEST_QUEUE_STORE_H_