Plumb thru that we cache the front buffer.

content/common/gpu/image_transport_surface_win.cc

Index: content/common/gpu/image_transport_surface_win.cc
diff --git a/content/common/gpu/image_transport_surface_win.cc b/content/common/gpu/image_transport_surface_win.cc
index f3eb9d5a318db6eaa44d5004f1abe915e4c36488..a33c4665f034810cefb07c7a0be28ee350982ae2 100644
--- a/content/common/gpu/image_transport_surface_win.cc
+++ b/content/common/gpu/image_transport_surface_win.cc
@@ -32,11 +32,13 @@ class PbufferImageTransportSurface
                                int32 renderer_id,
                                int32 command_buffer_id);
 
-  // GLSurface implementation
-  virtual bool Initialize();
-  virtual void Destroy();
-  virtual bool IsOffscreen();
-  virtual bool SwapBuffers();
+  // gfx::GLSurface implementation
+  virtual bool Initialize() OVERRIDE;
+  virtual void Destroy() OVERRIDE;
+  virtual bool IsOffscreen() OVERRIDE;
+  virtual bool SwapBuffers() OVERRIDE;
+  virtual bool PostSubBuffer(int x, int y, int width, int height) OVERRIDE;
+  virtual std::string GetExtensions() OVERRIDE;
 
  protected:
   // ImageTransportSurface implementation
@@ -109,6 +111,19 @@ bool PbufferImageTransportSurface::SwapBuffers() {
   return true;
 }
 
+bool PbufferImageTransportSurface::PostSubBuffer(
+    int x, int y, int width, int height) {
+  NOTREACHED();
+  return false;
+}
+
+std::string PbufferImageTransportSurface::GetExtensions() {
+  std::string extensions = gfx::GLSurface::GetExtensions();
+  extensions += extensions.empty() ? "" : " ";
+  extensions += "GL_CHROMIUM_front_buffer_cached";
+  return extensions;
+}
+
 void PbufferImageTransportSurface::SendBuffersSwapped() {
   GpuHostMsg_AcceleratedSurfaceBuffersSwapped_Params params;
   params.surface_id = reinterpret_cast<int64>(GetShareHandle());