extension_utils: Remove old files and update DEPS whitelist.

chrome/browser/ui/views/ash/extension_utils.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_BROWSER_UI_VIEWS_ASH_EXTENSION_UTILS_H_
-#define CHROME_BROWSER_UI_VIEWS_ASH_EXTENSION_UTILS_H_
-
-class Profile;
-
-namespace extensions {
-class Extension;
-}
-
-namespace extension_utils {
-
-// Opens an extension.  |event_flags| holds the flags of the event
-// which triggered this extension.
-void OpenExtension(Profile* profile,
-                   const extensions::Extension* extension,
-                   int event_flags);
-
-}  // namespace extension_utils
-
-#endif  // CHROME_BROWSER_UI_VIEWS_ASH_EXTENSION_UTILS_H_