Maintain minimal error response.

content/browser/frame_host/render_widget_host_view_guest.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_FRAME_HOST_RENDER_WIDGET_HOST_VIEW_GUEST_H_
 #define CONTENT_BROWSER_FRAME_HOST_RENDER_WIDGET_HOST_VIEW_GUEST_H_
 
 #include <vector>
 
 #include "base/memory/scoped_ptr.h"
@@ skipping 121 matching lines @@
   void SetParentNativeViewAccessible(
       gfx::NativeViewAccessible accessible_parent) override;
   gfx::NativeViewId GetParentForWindowlessPlugin() const override;
 #endif
 
   // Overridden from ui::GestureEventHelper.
   bool CanDispatchToConsumer(ui::GestureConsumer* consumer) override;
   void DispatchGestureEvent(ui::GestureEvent* event) override;
   void DispatchCancelTouchEvent(ui::TouchEvent* event) override;
 
-  SkColorType PreferredReadbackFormat() override;
-
  protected:
   friend class RenderWidgetHostView;
 
  private:
   // Destroys this view without calling |Destroy| on |platform_view_|.
   void DestroyGuestView();
 
   // Builds and forwards a WebKitGestureEvent to the renderer.
   bool ForwardGestureEventToRenderer(ui::GestureEvent* gesture);
 
@@ skipping 17 matching lines @@
   base::WeakPtr<RenderWidgetHostViewBase> platform_view_;
 #if defined(USE_AURA)
   scoped_ptr<ui::GestureRecognizer> gesture_recognizer_;
 #endif
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostViewGuest);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_FRAME_HOST_RENDER_WIDGET_HOST_VIEW_GUEST_H_