Associate an id with the output surface to handle lost contexts

content/renderer/render_widget.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_RENDERER_RENDER_WIDGET_H_
 #define CONTENT_RENDERER_RENDER_WIDGET_H_
 
 #include <deque>
 #include <map>
 
@@ skipping 705 matching lines @@
   bool is_threaded_compositing_enabled_;
 
   // The last set of rendering stats received from the browser. This is only
   // received when using the --enable-gpu-benchmarking flag.
   BrowserRenderingStats browser_rendering_stats_;
 
   // The latency information for any current non-accelerated-compositing
   // frame.
   ui::LatencyInfo latency_info_;
 
+  uint32 next_output_surface_id_;
+
   base::WeakPtrFactory<RenderWidget> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidget);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_RENDER_WIDGET_H_