Use a vector of smart pointers for callback return type.

components/offline_pages/background/request_coordinator.cc

 // 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.
 
 #include "components/offline_pages/background/request_coordinator.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/callback.h"
@@ skipping 89 matching lines @@
   // Get all matching requests from the request queue, send them to our
   // callback.  We bind the namespace and callback to the front of the callback
   // param set.
   queue_->GetRequests(base::Bind(&RequestCoordinator::GetQueuedRequestsCallback,
                                  weak_ptr_factory_.GetWeakPtr(), callback));
 }
 
 void RequestCoordinator::GetQueuedRequestsCallback(
     const GetRequestsCallback& callback,
     RequestQueue::GetRequestsResult result,
-    const std::vector<SavePageRequest>& requests) {
-  callback.Run(requests);
+    std::vector<std::unique_ptr<SavePageRequest>> requests) {
+  callback.Run(std::move(requests));
 }
 
 void RequestCoordinator::StopPrerendering() {
   if (offliner_ && is_busy_) {
     offliner_->Cancel();
     // Find current request and mark attempt aborted.
     active_request_->MarkAttemptAborted();
     queue_->UpdateRequest(*(active_request_.get()),
                           base::Bind(&RequestCoordinator::UpdateRequestCallback,
                                      weak_ptr_factory_.GetWeakPtr(),
@@ skipping 78 matching lines @@
   if (result != RequestQueue::UpdateRequestResult::SUCCESS) {
     DVLOG(1) << "Failed to update request attempt details. "
              << static_cast<int>(result);
     event_logger_.RecordUpdateRequestFailed(client_id.name_space, result);
   }
 }
 
 // Called in response to updating multiple requests in the request queue.
 void RequestCoordinator::UpdateMultipleRequestsCallback(
     const RequestQueue::UpdateMultipleRequestResults& results,
-    const std::vector<SavePageRequest>& requests) {
-  for (SavePageRequest request : requests)
-    NotifyChanged(request);
+    std::vector<std::unique_ptr<SavePageRequest>> requests) {
+  std::vector<std::unique_ptr<SavePageRequest>>::iterator request;

[Dmitry Titov, 2016/08/26 23:39:20]

would something like this work:
for (const auto& request : requests)
  NotifyChanged(request->get());

This would be more readable than iterator...

[Pete Williamson, 2016/08/27 00:11:59]

Done.

+  for (request = requests.begin(); request != requests.end(); ++request)
+    NotifyChanged(*(request->get()));
 }
 
 void RequestCoordinator::HandleRemovedRequestsAndCallback(
     const RemoveRequestsCallback& callback,
     const RequestQueue::UpdateMultipleRequestResults& results,
-    const std::vector<SavePageRequest>& requests) {
+    std::vector<std::unique_ptr<SavePageRequest>> requests) {
   callback.Run(results);
-  HandleRemovedRequests(results, requests);
+  HandleRemovedRequests(results, std::move(requests));
 }
 
 void RequestCoordinator::HandleRemovedRequests(
     const RequestQueue::UpdateMultipleRequestResults& results,
-    const std::vector<SavePageRequest>& requests) {
-  for (SavePageRequest request : requests)
-    NotifyCompleted(request, SavePageStatus::REMOVED);
+    std::vector<std::unique_ptr<SavePageRequest>> requests) {
+  std::vector<std::unique_ptr<SavePageRequest>>::iterator request;
+  for (request = requests.begin(); request != requests.end(); ++request)
+    NotifyCompleted(*(request->get()), SavePageStatus::REMOVED);
 }
 
 void RequestCoordinator::StopProcessing() {
   is_stopped_ = true;
   StopPrerendering();
 
   // Let the scheduler know we are done processing.
   scheduler_callback_.Run(true);
 }
 
@@ skipping 210 matching lines @@
   FOR_EACH_OBSERVER(Observer, observers_, OnChanged(request));
 }
 
 void RequestCoordinator::GetOffliner() {
   if (!offliner_) {
     offliner_ = factory_->GetOffliner(policy_.get());
   }
 }
 
 }  // namespace offline_pages