chrome: Cleanup class/struct forward declarations

chrome/browser/ui/views/frame/browser_desktop_window_tree_host.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_FRAME_BROWSER_DESKTOP_WINDOW_TREE_HOST_H_
 #define CHROME_BROWSER_UI_VIEWS_FRAME_BROWSER_DESKTOP_WINDOW_TREE_HOST_H_
 
 class BrowserFrame;
 class BrowserView;
-namespace gfx {
-class Rect;
-}
+
 namespace views {
 class DesktopNativeWidgetAura;
 class DesktopWindowTreeHost;
 namespace internal {
 class NativeWidgetDelegate;
 }
 }
 
 // Interface to a platform specific browser frame implementation. The object
 // implementing this interface will also implement views::DesktopWindowTreeHost.
@@ skipping 10 matching lines @@
 
   virtual int GetMinimizeButtonOffset() const = 0;
 
   // Returns true if the OS takes care of showing the system menu. Returning
   // false means BrowserFrame handles showing the system menu.
   virtual bool UsesNativeSystemMenu() const = 0;
 };
 
 
 #endif  // CHROME_BROWSER_UI_VIEWS_FRAME_BROWSER_DESKTOP_WINDOW_TREE_HOST_H_