content: Cleanup class/struct forward declarations

content/browser/renderer_host/render_widget_host_view_base.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_BASE_H_
 #define CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_BASE_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 24 matching lines @@
 #include "ui/base/ime/text_input_mode.h"
 #include "ui/base/ime/text_input_type.h"
 #include "ui/display/display.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/native_widget_types.h"
 #include "ui/gfx/range/range.h"
 #include "ui/surface/transport_dib.h"
 
 class SkBitmap;
 
-struct AccessibilityHostMsg_EventParams;
 struct ViewHostMsg_SelectionBounds_Params;
 
 namespace media {
 class VideoFrame;
 }
 
 namespace blink {
 class WebMouseEvent;
 class WebMouseWheelEvent;
 }
@@ skipping 444 matching lines @@
   base::ObserverList<RenderWidgetHostViewBaseObserver> observers_;
 
   base::WeakPtrFactory<RenderWidgetHostViewBase> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostViewBase);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_BASE_H_