Move chrome.fileSystem implementation to //extensions

extensions/common/api/file_system.idl

 // 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.
 
 // Use the <code>chrome.fileSystem</code> API to create, read, navigate,
 // and write to the user's local file system. With this API, Chrome Apps can
 // read and write to a user-selected location. For example, a text editor app
 // can use the API to read and write local documents. All failures are notified
 // via chrome.runtime.lastError.
 namespace fileSystem {
@@ skipping 214 matching lines @@
     // Called when a list of available volumes is changed.
     static void onVolumeListChanged(VolumeListChangedEvent event);
 
     // Called when an observed entry is changed.
     [nodoc] static void onEntryChanged(EntryChangedEvent event);
 
     // Called when an observed entry is removed.
     [nodoc] static void onEntryRemoved(EntryRemovedEvent event);
   };
 };