Require FilePathWatcher destructor to be called in sequence with Watch().

chrome/browser/media_galleries/fileapi/file_path_watcher_util.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_FILE_PATH_WATCHER_UTIL_H_
 #define CHROME_BROWSER_MEDIA_GALLERIES_FILEAPI_FILE_PATH_WATCHER_UTIL_H_
 
 #include <memory>
 
 #include "base/callback_forward.h"
 #include "base/files/file_path.h"
 #include "base/files/file_path_watcher.h"
 
 typedef base::Callback<void(std::unique_ptr<base::FilePathWatcher> watcher)>
     FileWatchStartedCallback;
 
 // Called on the MediaTaskRunner to begin a file watch.
 // |watch_started_callback| is responsible for taking ownership of the
 // file watcher upon start. All callbacks are run on the MediaTaskRunner.
 void StartFilePathWatchOnMediaTaskRunner(
     const base::FilePath& path,
     const FileWatchStartedCallback& watch_started_callback,
     const base::FilePathWatcher::Callback& path_changed_callback);
 
+// Stops a file path watch started by StartFilePathWatchOnMediaTaskRunner. Must

[Lei Zhang, 2016/11/10 18:59:31]

nit: I really like to refer to functions as FuncName() so it is obvious that it
is a function and not a class.

[fdoray, 2016/11/11 15:47:39]

Done.

+// be called from the MediaTaskRunner.
+void StopFilePathWatchOnMediaTaskRunner(
+    std::unique_ptr<base::FilePathWatcher> watcher);
+
 #endif  // CHROME_BROWSER_MEDIA_GALLERIES_FILEAPI_FILE_PATH_WATCHER_UTIL_H_