Prevent browser thumbnailer from trying to read from frontbuffer (surface texture) when none exists.

content/browser/renderer_host/render_widget_host_view_mac.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_MAC_H_
 #define CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_MAC_H_
 #pragma once
 
 #import <Cocoa/Cocoa.h>
 #include <list>
@@ skipping 172 matching lines @@
 
   // RenderWidgetHostView implementation.
   virtual void InitAsChild(gfx::NativeView parent_view) OVERRIDE;
   virtual content::RenderWidgetHost* GetRenderWidgetHost() const OVERRIDE;
   virtual void SetSize(const gfx::Size& size) OVERRIDE;
   virtual void SetBounds(const gfx::Rect& rect) OVERRIDE;
   virtual gfx::NativeView GetNativeView() const OVERRIDE;
   virtual gfx::NativeViewId GetNativeViewId() const OVERRIDE;
   virtual gfx::NativeViewAccessible GetNativeViewAccessible() OVERRIDE;
   virtual bool HasFocus() const OVERRIDE;
+  virtual bool HasSurface() const OVERRIDE;
   virtual void Show() OVERRIDE;
   virtual void Hide() OVERRIDE;
   virtual bool IsShowing() OVERRIDE;
   virtual gfx::Rect GetViewBounds() const OVERRIDE;
   virtual void SetShowingContextMenu(bool showing) OVERRIDE;
   virtual void SetActive(bool active) OVERRIDE;
   virtual void SetTakesFocusOnlyOnMouseDown(bool flag) OVERRIDE;
   virtual void SetWindowVisibility(bool visible) OVERRIDE;
   virtual void WindowFrameChanged() OVERRIDE;
   virtual void SetBackground(const SkBitmap& background) OVERRIDE;
@@ skipping 217 matching lines @@
   std::string selected_text_;
 
   // The fullscreen window used for pepper flash.
   scoped_nsobject<NSWindow> pepper_fullscreen_window_;
   scoped_nsobject<FullscreenWindowManager> fullscreen_window_manager_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostViewMac);
 };
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_MAC_H_