indexeddb: Removed use of dangling ptr in writeBlobToFileOnIOThread.

content/browser/indexed_db/indexed_db_context_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/indexed_db/indexed_db_context_impl.h"
 
 #include <algorithm>
 #include <utility>
 
 #include "base/bind.h"
@@ skipping 554 matching lines @@
   }
   return origin_set_.get();
 }
 
 void IndexedDBContextImpl::ResetCaches() {
   origin_set_.reset();
   origin_size_map_.clear();
   space_available_map_.clear();
 }
 
-base::TaskRunner* IndexedDBContextImpl::TaskRunner() const {
+base::SequencedTaskRunner* IndexedDBContextImpl::TaskRunner() const {
   return task_runner_;
 }
 
 }  // namespace content