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

content/browser/renderer_host/render_widget_host_view_gtk.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_GTK_H_
 #define CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_GTK_H_
 #pragma once
 
 #include <gdk/gdk.h>
 
@@ skipping 40 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 IsSurfaceAvailableForCopy() const OVERRIDE;
   virtual void Show() OVERRIDE;
   virtual void Hide() OVERRIDE;
   virtual bool IsShowing() OVERRIDE;
   virtual gfx::Rect GetViewBounds() const OVERRIDE;
   virtual GdkEventButton* GetLastMouseDown() OVERRIDE;
   virtual gfx::NativeView BuildInputMethodsGtkMenu() OVERRIDE;
   virtual void SetBackground(const SkBitmap& background) OVERRIDE;
 
   // RenderWidgetHostViewPort implementation.
   virtual void InitAsPopup(content::RenderWidgetHostView* parent_host_view,
@@ skipping 236 matching lines @@
   GdkEventButton* last_mouse_down_;
 
   // Instance of accessibility information for the root of the AtkObject
   // tree representation of the WebKit render tree.
   scoped_ptr<BrowserAccessibilityManager> browser_accessibility_manager_;
 
   ui::GtkSignalRegistrar signals_;
 };
 
 #endif  // CHROME_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_GTK_H_