Revert of Make lost context and error message callbacks on GpuControl go to client

mojo/gles2/gles2_context.h

Index: mojo/gles2/gles2_context.h
diff --git a/mojo/gles2/gles2_context.h b/mojo/gles2/gles2_context.h
index 3d4d92e00533a8343877c6460a7174969d6f39ee..e5dac20225387efca48eff451f9aada3168e4352 100644
--- a/mojo/gles2/gles2_context.h
+++ b/mojo/gles2/gles2_context.h
@@ -27,13 +27,14 @@
 
 namespace gles2 {
 
-class GLES2Context : public MojoGLES2ContextPrivate {
+class GLES2Context : public CommandBufferDelegate,
+                     public MojoGLES2ContextPrivate {
  public:
   explicit GLES2Context(const std::vector<int32_t>& attribs,
                         mojo::ScopedMessagePipeHandle command_buffer_handle,
                         MojoGLES2ContextLost lost_callback,
                         void* closure);
-  virtual ~GLES2Context();
+  ~GLES2Context() override;
   bool Initialize();
 
   gpu::gles2::GLES2Interface* interface() const {
@@ -42,7 +43,7 @@
   gpu::ContextSupport* context_support() const { return implementation_.get(); }
 
  private:
-  void OnLostContext();
+  void ContextLost() override;
 
   CommandBufferClientImpl command_buffer_;
   scoped_ptr<gpu::gles2::GLES2CmdHelper> gles2_helper_;