Plumb file system name down from MediaFileSystemRegistry.

chrome/common/extensions/extension_constants.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_COMMON_EXTENSIONS_EXTENSION_CONSTANTS_H_
 #define CHROME_COMMON_EXTENSIONS_EXTENSION_CONSTANTS_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 233 matching lines @@
 
   // The states that an app can be in, as reported by chrome.app.installState
   // and chrome.app.runningState.
   extern const char kAppStateNotInstalled[];
   extern const char kAppStateInstalled[];
   extern const char kAppStateDisabled[];
   extern const char kAppStateRunning[];
   extern const char kAppStateCannotRun[];
   extern const char kAppStateReadyToRun[];
 
+  // The path part of the file system url used for media file systems.
+  extern const char kMediaFileSystemPathPart[];
+
   // Error indicating that the app notifications API is not accessible by split
   // mode extensions in incognito windows.
   extern const char kAppNotificationsIncognitoError[];
 }  // extension_misc
 
 #endif  // CHROME_COMMON_EXTENSIONS_EXTENSION_CONSTANTS_H_