Convert ppapi/shared to use TrackedCallback.

ppapi/proxy/ppb_graphics_3d_proxy.h

Index: ppapi/proxy/ppb_graphics_3d_proxy.h
diff --git a/ppapi/proxy/ppb_graphics_3d_proxy.h b/ppapi/proxy/ppb_graphics_3d_proxy.h
index 5a6c33402519447690440457022e9859d738d0cf..f4110b6adaa55129847ead75607fd813ea09e54d 100644
--- a/ppapi/proxy/ppb_graphics_3d_proxy.h
+++ b/ppapi/proxy/ppb_graphics_3d_proxy.h
@@ -23,18 +23,13 @@ class HostResource;
 
 namespace proxy {
 
-class Graphics3D : public Resource, public PPB_Graphics3D_Shared {
+class Graphics3D : public PPB_Graphics3D_Shared {
  public:
   explicit Graphics3D(const HostResource& resource);
   virtual ~Graphics3D();
 
   bool Init();
 
-  // Resource overrides.
-  virtual thunk::PPB_Graphics3D_API* AsPPB_Graphics3D_API() OVERRIDE {
-    return this;
-  }
-
   // Graphics3DTrusted API. These are not implemented in the proxy.
   virtual PP_Bool InitCommandBuffer() OVERRIDE;
   virtual PP_Bool SetGetBuffer(int32_t shm_id) OVERRIDE;