content: Cleanup class/struct forward declarations

content/browser/web_contents/aura/overscroll_navigation_overlay.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 CONTENT_BROWSER_WEB_CONTENTS_AURA_OVERSCROLL_NAVIGATION_OVERLAY_H_
 #define CONTENT_BROWSER_WEB_CONTENTS_AURA_OVERSCROLL_NAVIGATION_OVERLAY_H_
 
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "content/browser/web_contents/aura/overscroll_window_animation.h"
 #include "content/browser/web_contents/web_contents_view_aura.h"
 #include "content/common/content_export.h"
 #include "content/public/browser/web_contents_observer.h"
 #include "ui/gfx/image/image.h"
 
-struct ViewHostMsg_UpdateRect_Params;
-
 namespace content {
 
-class OverscrollWindowDelegate;
 class OverscrollNavigationOverlayTest;
 
 // When a history navigation is triggered at the end of an overscroll
 // navigation, it is necessary to show the history-screenshot until the page is
 // done navigating and painting. This class accomplishes this by calling the
 // navigation and creating, showing and destroying the screenshot window on top
 // of the page until the page has completed loading and painting. When the
 // overscroll completes, this screenshot window is returned by
 // OnOverscrollComplete and |window_| is set to own it.
 // There are two overscroll cases, for the first one the main window is the web
@@ skipping 87 matching lines @@
 
   // The window that hosts the web contents.
   aura::Window* web_contents_window_;
 
   DISALLOW_COPY_AND_ASSIGN(OverscrollNavigationOverlay);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_WEB_CONTENTS_AURA_OVERSCROLL_NAVIGATION_OVERLAY_H_