[Mac] Cmd+W should close the User Manager

chrome/browser/ui/cocoa/profiles/user_manager_mac.h

 // Copyright 2014 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_COCOA_PROFILES_USER_MANAGER_MAC_H_
 #define CHROME_BROWSER_UI_COCOA_PROFILES_USER_MANAGER_MAC_H_
 
 #import <Cocoa/Cocoa.h>
 
 #include "base/mac/scoped_nsobject.h"
 #include "base/memory/scoped_ptr.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/profiles/profile_window.h"
 
-class UserManagerMac;
 @class UserManagerWindowController;
 
 namespace content {
 class NavigationController;
 class WebContents;
 }
 
 // Dialog widget that contains the Desktop User Manager webui.
 class UserManagerMac {
  public:
@@ skipping 27 matching lines @@
   // is reset to NULL when the window is closed.
   static UserManagerMac* instance_;  // Weak.
 
   // Controller of the window.
   base::scoped_nsobject<UserManagerWindowController> window_controller_;
 
   DISALLOW_COPY_AND_ASSIGN(UserManagerMac);
 };
 
 #endif  // CHROME_BROWSER_UI_COCOA_PROFILES_USER_MANAGER_MAC_H_