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

content/browser/renderer_host/render_widget_host_view_aura.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_AURA_H_
 #define CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_AURA_H_
 #pragma once
 
 #include <map>
 #include <vector>
@@ skipping 43 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 void SetBackground(const SkBitmap& background) OVERRIDE;
 
   // Overridden from RenderWidgetHostViewPort:
   virtual void InitAsPopup(content::RenderWidgetHostView* parent_host_view,
                            const gfx::Rect& pos) OVERRIDE;
   virtual void InitAsFullscreen(
@@ skipping 227 matching lines @@
   // These locks are the ones waiting for a texture of the right size to come
   // back from the renderer/GPU process.
   std::vector<linked_ptr<ResizeLock> > resize_locks_;
   // These locks are the ones waiting for a frame to be drawn.
   std::vector<linked_ptr<ResizeLock> > locks_pending_draw_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostViewAura);
 };
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_AURA_H_