Fix threading bug in the brlapi braille controller

chrome/browser/extensions/api/braille_display_private/braille_controller_brlapi.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_EXTENSIONS_API_BRAILLE_DISPLAY_PRIVATE_BRAILLE_CONTROLLER_BRLAPI_H_
 #define CHROME_BROWSER_EXTENSIONS_API_BRAILLE_DISPLAY_PRIVATE_BRAILLE_CONTROLLER_BRLAPI_H_
 
 #include "base/files/file_path.h"
 #include "base/files/file_path_watcher.h"
 #include "base/gtest_prod_util.h"
@@ skipping 34 matching lines @@
   void SetCreateBrlapiConnectionForTesting(
       const CreateBrlapiConnectionFunction& callback);
 
   // Makes the controller try to reconnect (if disconnected) as if the brlapi
   // socket directory had changed.
   void PokeSocketDirForTesting();
 
   // Tries to connect and starts watching for new brlapi servers.
   // No-op if already called.
   void StartConnecting();
-  void OnSocketDirChanged(const base::FilePath& path, bool error);
+  void StartWatchingSocketDirOnFileThread();
+  void OnSocketDirChangedOnFileThread(const base::FilePath& path, bool error);
+  void OnSocketDirChangedOnIOThread();
   void TryToConnect();
   void ResetRetryConnectHorizon();
   void ScheduleTryToConnect();
   void Disconnect();
   scoped_ptr<BrlapiConnection> CreateBrlapiConnection();
   void DispatchKeys();
   scoped_ptr<KeyEvent> MapKeyCode(brlapi_keyCode_t code);
   void DispatchKeyEvent(scoped_ptr<KeyEvent> event);
   void DispatchOnDisplayStateChanged(scoped_ptr<DisplayState> new_state);
 
-  LibBrlapiLoader libbrlapi_loader_;
   CreateBrlapiConnectionFunction create_brlapi_connection_function_;
 
   // Manipulated on the IO thread.
+  LibBrlapiLoader libbrlapi_loader_;
   scoped_ptr<BrlapiConnection> connection_;
-  base::FilePathWatcher file_path_watcher_;
   bool started_connecting_;
   bool connect_scheduled_;
   base::Time retry_connect_horizon_;
 
   // Manipulated on the UI thread.
   ObserverList<BrailleObserver> observers_;
 
+  // Manipulated on the FILE thread.
+  base::FilePathWatcher file_path_watcher_;
+
   friend struct DefaultSingletonTraits<BrailleControllerImpl>;
 
   DISALLOW_COPY_AND_ASSIGN(BrailleControllerImpl);
 };
 
 }  // namespace braille_display_private
 }  // namespace api
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_BRAILLE_DISPLAY_PRIVATE_BRAILLE_CONTROLLER_BRLAPI_H_