Maintain minimal error response.

content/browser/frame_host/render_widget_host_view_guest.cc

 // 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.
 
 #include "base/bind_helpers.h"
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/message_loop/message_loop.h"
 #include "content/browser/browser_plugin/browser_plugin_guest.h"
 #include "content/browser/frame_host/render_widget_host_view_guest.h"
@@ skipping 534 matching lines @@
     ui::GestureRecognizer::Gestures* gestures) {
   if ((gestures == NULL) || gestures->empty())
     return;
   for (ui::GestureRecognizer::Gestures::iterator g_it = gestures->begin();
       g_it != gestures->end();
       ++g_it) {
     ForwardGestureEventToRenderer(*g_it);
   }
 }
 
-SkColorType RenderWidgetHostViewGuest::PreferredReadbackFormat() {
-  return kN32_SkColorType;
-}
-
 RenderWidgetHostViewBase*
 RenderWidgetHostViewGuest::GetOwnerRenderWidgetHostView() const {
   return static_cast<RenderWidgetHostViewBase*>(
       guest_->GetOwnerRenderWidgetHostView());
 }
 
 void RenderWidgetHostViewGuest::OnHandleInputEvent(
     RenderWidgetHostImpl* embedder,
     int browser_plugin_instance_id,
     const gfx::Rect& guest_window_rect,
@@ skipping 26 matching lines @@
   }
 
   if (blink::WebInputEvent::isGestureEventType(event->type)) {
     host_->ForwardGestureEvent(
         *static_cast<const blink::WebGestureEvent*>(event));
     return;
   }
 }
 
 }  // namespace content