Adds an observer for the request coordinator.

components/offline_pages/background/request_queue_store_sql.h

Index: components/offline_pages/background/request_queue_store_sql.h
diff --git a/components/offline_pages/background/request_queue_store_sql.h b/components/offline_pages/background/request_queue_store_sql.h
index 10631dc6c4e84766595396c00e8ff88d5af5e1e2..3e8e0b963ed614881cd9c377f6fb3c8a5e0c9ecd 100644
--- a/components/offline_pages/background/request_queue_store_sql.h
+++ b/components/offline_pages/background/request_queue_store_sql.h
@@ -38,9 +38,10 @@ class RequestQueueStoreSQL : public RequestQueueStore {
                           const UpdateCallback& callback) override;
   void RemoveRequests(const std::vector<int64_t>& request_ids,
                       const RemoveCallback& callback) override;
-  void ChangeRequestsState(const std::vector<int64_t>& request_ids,
-                           const SavePageRequest::RequestState new_state,
-                           const UpdateCallback& callback) override;
+  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:
@@ -67,7 +68,7 @@ class RequestQueueStoreSQL : public RequestQueueStore {
       scoped_refptr<base::SingleThreadTaskRunner> runner,
       const std::vector<int64_t>& request_ids,
       const SavePageRequest::RequestState new_state,
-      const UpdateCallback& callback);
+      const UpdateMultipleRequestsCallback& callback);
   static void ResetSync(sql::Connection* db,
                         const base::FilePath& db_file_path,
                         scoped_refptr<base::SingleThreadTaskRunner> runner,