[Offline Pages] Turn Offliner::Cancel into an async operation to resolve conflicting assumptions

chrome/browser/android/offline_pages/prerendering_offliner.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 "chrome/browser/android/offline_pages/prerendering_offliner.h"
 
 #include "base/bind.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/sys_info.h"
 #include "chrome/browser/android/offline_pages/offline_page_mhtml_archiver.h"
@@ skipping 173 matching lines @@
   } else {
     // Create app listener for the pending request.
     app_listener_.reset(new base::android::ApplicationStatusListener(
         base::Bind(&PrerenderingOffliner::OnApplicationStateChange,
                    weak_ptr_factory_.GetWeakPtr())));
   }
 
   return accepted;
 }
 
-void PrerenderingOffliner::Cancel() {
+void PrerenderingOffliner::Cancel(const CancelCallback& callback) {
+  int64_t request_id = 0L;

[fgorski, 2017/02/27 18:07:25]

0LL?

[chili, 2017/02/28 00:44:14]

Done.

   if (pending_request_) {
+    request_id = pending_request_->request_id();
     pending_request_.reset(nullptr);
     app_listener_.reset(nullptr);
     GetOrCreateLoader()->StopLoading();
     // TODO(dougarnett): Consider ability to cancel SavePage request.
   }
+  callback.Run(request_id);
 }
 
 void PrerenderingOffliner::SetLoaderForTesting(
     std::unique_ptr<PrerenderingLoader> loader) {
   DCHECK(!loader_);
   loader_ = std::move(loader);
 }
 
 void PrerenderingOffliner::SetLowEndDeviceForTesting(bool is_low_end_device) {
   is_low_end_device_ = is_low_end_device;
@@ skipping 20 matching lines @@
   return loader_.get();
 }
 
 void PrerenderingOffliner::OnApplicationStateChange(
     base::android::ApplicationState application_state) {
   if (pending_request_ && is_low_end_device_ &&
       application_state ==
           base::android::APPLICATION_STATE_HAS_RUNNING_ACTIVITIES) {
     DVLOG(1) << "App became active, canceling current offlining request";
     SavePageRequest* request = pending_request_.get();
-    Cancel();
-    completion_callback_.Run(*request,
-                             Offliner::RequestStatus::FOREGROUND_CANCELED);
+    Cancel(base::Bind(&PrerenderingOffliner::HandleApplicationStateChangeCancel,

[fgorski, 2017/02/27 18:07:25]

add the same comment as before please.

[chili, 2017/02/28 00:44:14]

Done.

+                      weak_ptr_factory_.GetWeakPtr(), *request));
   }
 }
 
+void PrerenderingOffliner::HandleApplicationStateChangeCancel(
+    const SavePageRequest& request,
+    int64_t offline_id) {
+  completion_callback_.Run(request, RequestStatus::FOREGROUND_CANCELED);
+}
 }  // namespace offline_pages