content: Cleanup class/struct forward declarations

content/browser/renderer_host/render_widget_host_view_aura.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 CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_AURA_H_
 #define CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_AURA_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 32 matching lines @@
 #include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/selection_bound.h"
 #include "ui/wm/public/activation_delegate.h"
 
 namespace aura {
 namespace client {
 class ScopedTooltipDisabler;
 }
 }
 
-namespace cc {
-class CopyOutputRequest;
-class CopyOutputResult;
-}
-
 namespace gfx {
-class Canvas;
 class Display;
 class Point;
 class Rect;
 }
 
-namespace gpu {
-struct Mailbox;
-}
-
 namespace ui {
-class CompositorLock;
 class InputMethod;
 class LocatedEvent;
 #if defined(OS_WIN)
 class OnScreenKeyboardObserver;
 #endif
-class Texture;
 class TouchSelectionController;
 }
 
 namespace content {
 #if defined(OS_WIN)
 class LegacyRenderWidgetHostHWND;
 #endif
 
 class OverscrollController;
 class RenderFrameHostImpl;
-class RenderViewHostDelegateView;
 class RenderWidgetHostImpl;
 class RenderWidgetHostView;
 class TouchSelectionControllerClientAura;
 struct TextInputState;
 
 // RenderWidgetHostView class hierarchy described in render_widget_host_view.h.
 class CONTENT_EXPORT RenderWidgetHostViewAura
     : public RenderWidgetHostViewBase,
       NON_EXPORTED_BASE(public RenderWidgetHostViewEventHandler::Delegate),
       public DelegatedFrameHostClient,
@@ skipping 516 matching lines @@
   std::unique_ptr<RenderWidgetHostViewEventHandler> event_handler_;
 
   base::WeakPtrFactory<RenderWidgetHostViewAura> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostViewAura);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_AURA_H_