Try to flush DOMStorage too when ending the browsing session.

content/browser/storage_partition_impl.cc

 // Copyright (c) 2012 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 "content/browser/storage_partition_impl.h"
 
 #include <stddef.h>
 
 #include <set>
 #include <vector>
@@ skipping 876 matching lines @@
   if (url_matcher.is_null()) {
     StoragePartitionHttpCacheDataRemover::CreateForRange(this, begin, end)
         ->Remove(callback);
   } else {
     StoragePartitionHttpCacheDataRemover::CreateForURLsAndRange(
         this, url_matcher, begin, end)
         ->Remove(callback);
   }
 }
 
-void StoragePartitionImpl::Flush() {
+std::vector<scoped_refptr<base::SequencedTaskRunner>>
+StoragePartitionImpl::Flush() {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
-  if (GetDOMStorageContext())
-    GetDOMStorageContext()->Flush();
+  std::vector<scoped_refptr<base::SequencedTaskRunner>> flush_runners;
+  if (dom_storage_context_)
+    flush_runners = dom_storage_context_->Flush();
+  return flush_runners;
 }
 
 void StoragePartitionImpl::ClearBluetoothAllowedDevicesMapForTesting() {
   bluetooth_allowed_devices_map_->Clear();
 }
 
 BrowserContext* StoragePartitionImpl::browser_context() const {
   return browser_context_;
 }
 
@@ skipping 22 matching lines @@
   media_url_request_context_ = media_url_request_context;
 }
 
 void StoragePartitionImpl::GetQuotaSettings(
     const storage::OptionalQuotaSettingsCallback& callback) {
   GetContentClient()->browser()->GetQuotaSettings(browser_context_, this,
                                                   callback);
 }
 
 }  // namespace content