base: Re-apply WeakPtr support for SequencedWorkerPools, fixing deadlock

chrome/browser/storage_monitor/storage_monitor.h

 // 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.
 
 #ifndef CHROME_BROWSER_STORAGE_MONITOR_STORAGE_MONITOR_H_
 #define CHROME_BROWSER_STORAGE_MONITOR_STORAGE_MONITOR_H_
 
 #include <map>
 #include <string>
 #include <vector>
 
 #include "base/callback.h"
 #include "base/files/file_path.h"
 #include "base/observer_list_threadsafe.h"
 #include "base/strings/string16.h"
 #include "base/synchronization/lock.h"
+#include "base/threading/thread_checker.h"
 #include "chrome/browser/storage_monitor/storage_info.h"
 
 class ChromeBrowserMainPartsLinux;
 class ChromeBrowserMainPartsMac;
 class MediaGalleriesPlatformAppBrowserTest;
 class MediaGalleriesPrivateApiTest;
 class MediaGalleriesPrivateEjectApiTest;
 class SystemStorageApiTest;
 class SystemStorageEjectApiTest;
 
@@ skipping 152 matching lines @@
 
   // Map of all known storage devices,including fixed and removable storages.
   StorageMap storage_map_;
 
   scoped_ptr<TransientDeviceIds> transient_device_ids_;
 };
 
 }  // namespace chrome
 
 #endif  // CHROME_BROWSER_STORAGE_MONITOR_STORAGE_MONITOR_H_