Add reference-counting for mailbox textures.

content/common/gpu/texture_image_transport_surface.h

Index: content/common/gpu/texture_image_transport_surface.h
diff --git a/content/common/gpu/texture_image_transport_surface.h b/content/common/gpu/texture_image_transport_surface.h
index 93a54c5d7dfd9a8079b095e3fc6e59a2efd91053..a61649a50a9637e5270f946c9d6f1eef1e547a8d 100644
--- a/content/common/gpu/texture_image_transport_surface.h
+++ b/content/common/gpu/texture_image_transport_surface.h
@@ -8,6 +8,7 @@
 #include <string>
 
 #include "base/basictypes.h"
+#include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "content/common/gpu/gpu_command_buffer_stub.h"
 #include "content/common/gpu/image_transport_surface.h"
@@ -23,7 +24,8 @@ class GpuChannelManager;
 class TextureImageTransportSurface
     : public ImageTransportSurface,
       public GpuCommandBufferStub::DestructionObserver,
-      public gfx::GLSurface {
+      public gfx::GLSurface,
+      private gpu::gles2::TextureDefinition::Client {
  public:
   TextureImageTransportSurface(GpuChannelManager* manager,
                                GpuCommandBufferStub* stub,
@@ -82,7 +84,7 @@ class TextureImageTransportSurface
   uint32 fbo_id_;
 
   // The current backbuffer.
-  scoped_ptr<gpu::gles2::TextureDefinition> backbuffer_;
+  gpu::gles2::TextureDefinition* backbuffer_;
 
   // The mailbox name for the current backbuffer texture. Needs to be unique per
   // GL texture and is invalid while service_id is zero.
@@ -105,9 +107,6 @@ class TextureImageTransportSurface
   // the actual rendering is always redirected to an FBO.
   scoped_refptr<gfx::GLSurface> surface_;
 
-  // Holds a reference to the underlying context for cleanup.
-  scoped_refptr<gfx::GLContext> context_;
-
   // Whether a SwapBuffers is pending.
   bool is_swap_buffers_pending_;