Drop frontbuffers with ui-use-gpu-process, synchronized with browser, decoupled from backbuffer dro…

content/common/gpu/image_transport_surface_win.cc

 // 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.
 
 #if defined(ENABLE_GPU)
 
 #include "content/common/gpu/image_transport_surface.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
@@ skipping 31 matching lines @@
   virtual std::string GetExtensions() OVERRIDE;
   virtual void SetBufferAllocation(BufferAllocationState state) OVERRIDE;
 
  protected:
   // ImageTransportSurface implementation
   virtual void OnNewSurfaceACK(uint64 surface_handle,
                                TransportDIB::Handle shm_handle) OVERRIDE;
   virtual void OnBuffersSwappedACK() OVERRIDE;
   virtual void OnPostSubBufferACK() OVERRIDE;
   virtual void OnResizeViewACK() OVERRIDE;
+  virtual void OnDiscardSurface(uint64 surface_id) OVERRIDE;
   virtual void OnResize(gfx::Size size) OVERRIDE;
 
  private:
   virtual ~PbufferImageTransportSurface();
   void SendBuffersSwapped();
   void DestroySurface();
 
   // Tracks the current buffer allocation state.
   BufferAllocationState buffer_allocation_state_;
 
@@ skipping 118 matching lines @@
 void PbufferImageTransportSurface::OnNewSurfaceACK(
     uint64 surface_handle,
     TransportDIB::Handle shm_handle) {
   NOTREACHED();
 }
 
 void PbufferImageTransportSurface::OnResizeViewACK() {
   NOTREACHED();
 }
 
+void PbufferImageTransportSurface::OnDiscardSurface(uint64 surface_id) {
+}
+
 void PbufferImageTransportSurface::OnResize(gfx::Size size) {
   if (buffer_allocation_state_ == BUFFER_ALLOCATION_FRONT_AND_BACK)
     Resize(size);
 
   DestroySurface();
 
   visible_size_ = size;
 }
 
 }  // namespace anonymous
@@ skipping 28 matching lines @@
                                                    handle.transport);
   }
 
   if (surface->Initialize())
     return surface;
   else
     return NULL;
 }
 
 #endif  // ENABLE_GPU