Cleanup: Remove unneeded forward declarations from remoting.

remoting/host/disconnect_window_mac.h

 // Copyright (c) 2011 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.
 
 #import <Cocoa/Cocoa.h>
 
 namespace remoting {
 class ChromotingHost;
-class DisconnectWindowMac;
 }
 
 // Controller for the disconnect window which allows the host user to
 // quickly disconnect a session.
 @interface DisconnectWindowController : NSWindowController {
  @private
   remoting::ChromotingHost* host_;
   NSString* username_;
   IBOutlet NSTextField* connectedToField_;
   IBOutlet NSButton* disconnectButton_;
 }
 
 - (id)initWithHost:(remoting::ChromotingHost*)host
           username:(NSString*)username;
 - (IBAction)stopSharing:(id)sender;
 @end
 
 // A floating window with a custom border. The custom border and background
 // content is defined by DisconnectView. Declared here so that it can be
 // instantiated via a xib.
 @interface DisconnectWindow : NSWindow
 @end
 
 // The custom background/border for the DisconnectWindow. Declared here so that
 // it can be instantiated via a xib.
 @interface DisconnectView : NSView
 @end