Use a vector of smart pointers for callback return type.

components/offline_pages/background/request_queue.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_H_
 #define COMPONENTS_OFFLINE_PAGES_BACKGROUND_REQUEST_QUEUE_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 32 matching lines @@
     REQUEST_DOES_NOT_EXIST,  // Failed to delete the request because it does not
                              // exist.
   };
 
   // Type for a pair of request_id and result.
   typedef std::vector<std::pair<int64_t, UpdateRequestResult>>
       UpdateMultipleRequestResults;
 
   // Callback used for |GetRequests|.
   typedef base::Callback<void(GetRequestsResult,
-                              const std::vector<SavePageRequest>&)>
+                              std::vector<std::unique_ptr<SavePageRequest>>)>
       GetRequestsCallback;
 
   // Callback used for |AddRequest|.
   typedef base::Callback<void(AddRequestResult, const SavePageRequest& request)>
       AddRequestCallback;
 
   // Callback used by |UdpateRequest|.
   typedef base::Callback<void(UpdateRequestResult)> UpdateRequestCallback;
 
   // Callback used by |ChangeState| for more than one update at a time.
-  typedef base::Callback<void(const UpdateMultipleRequestResults& results,
-                              const std::vector<SavePageRequest>& requests)>
+  typedef base::Callback<void(
+      const UpdateMultipleRequestResults& results,
+      std::vector<std::unique_ptr<SavePageRequest>> requests)>
       UpdateMultipleRequestsCallback;
 
   // Callback used by |RemoveRequests|.
-  typedef base::Callback<void(const UpdateMultipleRequestResults& results,
-                              const std::vector<SavePageRequest>& requests)>
+  typedef base::Callback<void(
+      const UpdateMultipleRequestResults& results,
+      std::vector<std::unique_ptr<SavePageRequest>> requests)>
       RemoveRequestsCallback;
 
   explicit RequestQueue(std::unique_ptr<RequestQueueStore> store);
   ~RequestQueue();
 
   // Gets all of the active requests from the store. Calling this method may
   // schedule purging of the request queue.
   void GetRequests(const GetRequestsCallback& callback);
 
   // Adds |request| to the request queue. Result is returned through |callback|.
@@ skipping 20 matching lines @@
   // modify this to have a single update function that updates an entire
   // request, and doesn't need to care what updates.
   void ChangeRequestsState(const std::vector<int64_t>& request_ids,
                            const SavePageRequest::RequestState new_state,
                            const UpdateMultipleRequestsCallback& callback);
 
   void GetForUpdateDone(
       const RequestQueue::UpdateRequestCallback& update_callback,
       const SavePageRequest& update_request,
       bool success,
-      const std::vector<SavePageRequest>& requests);
+      std::vector<std::unique_ptr<SavePageRequest>> requests);
 
  private:
   // Callback used by |PurgeRequests|.
   typedef base::Callback<void(UpdateRequestResult,
                               int /* removed requests count */)>
       PurgeRequestsCallback;
 
   // Purges the queue, removing the requests that are no longer relevant, e.g.
   // expired request. Result is returned through |callback| carries the number
   // of removed requests.
   void PurgeRequests(const PurgeRequestsCallback& callback);
 
   std::unique_ptr<RequestQueueStore> store_;
 
   // Allows us to pass a weak pointer to callbacks.
   base::WeakPtrFactory<RequestQueue> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RequestQueue);
 };
 
 }  // namespace offline_pages
 
 #endif  // COMPONENTS_OFFLINE_PAGES_BACKGROUND_REQUEST_QUEUE_H_