Associate an id with the output surface to handle lost contexts

content/renderer/gpu/mailbox_output_surface.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_GPU_MAILBOX_OUTPUT_SURFACE_H_
 #define CONTENT_RENDERER_GPU_MAILBOX_OUTPUT_SURFACE_H_
 
 #include <queue>
 
 #include "cc/resources/transferable_resource.h"
 #include "content/renderer/gpu/compositor_output_surface.h"
 #include "ui/gfx/size.h"
 
 namespace cc {
 class CompositorFrameAck;
 }
 
 namespace content {
 
 // Implementation of CompositorOutputSurface that renders to textures which
 // are sent to the browser through the mailbox extension.
 // This class can be created only on the main thread, but then becomes pinned
 // to a fixed thread when bindToClient is called.
 class MailboxOutputSurface : public CompositorOutputSurface {
  public:
   MailboxOutputSurface(int32 routing_id,
+                       uint32 output_surface_id,
                        WebGraphicsContext3DCommandBufferImpl* context3d,
                        cc::SoftwareOutputDevice* software);
   virtual ~MailboxOutputSurface();
 
   // cc::OutputSurface implementation.
   virtual void EnsureBackbuffer() OVERRIDE;
   virtual void DiscardBackbuffer() OVERRIDE;
   virtual void Reshape(gfx::Size size, float scale_factor) OVERRIDE;
   virtual void BindFramebuffer() OVERRIDE;
   virtual void SwapBuffers(cc::CompositorFrame* frame) OVERRIDE;
 
  private:
   // CompositorOutputSurface overrides.
-  virtual void OnSwapAck(const cc::CompositorFrameAck& ack) OVERRIDE;
+  virtual void OnSwapAck(uint32 output_surface_id,
+                         const cc::CompositorFrameAck& ack) OVERRIDE;
 
   size_t GetNumAcksPending();
 
   struct TransferableFrame {
     TransferableFrame() : texture_id(0), sync_point(0) {}
 
     TransferableFrame(uint32 texture_id,
                       const gpu::Mailbox& mailbox,
                       const gfx::Size size)
         : texture_id(texture_id), mailbox(mailbox), size(size), sync_point(0) {}
 
     uint32 texture_id;
     gpu::Mailbox mailbox;
     gfx::Size size;
     uint32 sync_point;
   };
 
   TransferableFrame current_backing_;
   std::deque<TransferableFrame> pending_textures_;
   std::queue<TransferableFrame> returned_textures_;
 
   uint32 fbo_;
   bool is_backbuffer_discarded_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_GPU_MAILBOX_OUTPUT_SURFACE_H_