Always delete media galleries FilePathWatchers on the FILE thread.

chrome/browser/media_galleries/fileapi/iapps_data_provider.h

 // Copyright 2013 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_MEDIA_GALLERIES_FILEAPI_IAPPS_DATA_PROVIDER_H_
 #define CHROME_BROWSER_MEDIA_GALLERIES_FILEAPI_IAPPS_DATA_PROVIDER_H_
 
 #include <map>
 #include <memory>
 #include <set>
 #include <string>
 
 #include "base/callback_forward.h"
 #include "base/files/file_path.h"
 #include "base/files/file_path_watcher.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
+#include "chrome/browser/media_galleries/fileapi/file_path_watcher_util.h"
 
 namespace iapps {
 
 // This class is the holder for iTunes parsed data. Given a path to the iTunes
 // library XML file it will read it in, parse the data, and provide convenient
 // methods to access it.  When the file changes, it will update the data.
 // It is not thread safe, but can be run on any thread with IO access.
 class IAppsDataProvider {
  public:
   typedef base::Callback<void(bool)> ReadyCallback;
@@ skipping 18 matching lines @@
   // should be called when parsing has finished.
   virtual void DoParseLibrary(const base::FilePath& library_path,
                               const ReadyCallback& ready_callback) = 0;
 
   // Called when |library_path_| has changed. Virtual for testing.
   virtual void OnLibraryChanged(const base::FilePath& path, bool error);
 
  private:
   // Called when the FilePathWatcher for |library_path_| has tried to add an
   // watch.
-  void OnLibraryWatchStarted(
-      std::unique_ptr<base::FilePathWatcher> library_watcher);
+  void OnLibraryWatchStarted(MediaFilePathWatcherUniquePtr library_watcher);
 
   // Path to the library XML file.
   const base::FilePath library_path_;
 
   // True if the data needs to be refreshed from disk.
   bool needs_refresh_;
 
   // True if |library_| contains valid data. False at construction and if
   // reading or parsing the XML file fails.
   bool is_valid_;
 
   // A watcher on the library xml file.
-  std::unique_ptr<base::FilePathWatcher> library_watcher_;
+  MediaFilePathWatcherUniquePtr library_watcher_;
 
   base::WeakPtrFactory<IAppsDataProvider> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(IAppsDataProvider);
 };
 
 }  // namespace iapps
 
 #endif  // CHROME_BROWSER_MEDIA_GALLERIES_FILEAPI_IAPPS_DATA_PROVIDER_H_