Teach the native viewport service to draw a Surface into itself

mojo/examples/sample_app/sample_app.cc

 // Copyright 2013 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.
 
 #include <stdio.h>
 #include <string>
 
 #include "mojo/examples/sample_app/gles2_client_impl.h"
 #include "mojo/public/c/system/main.h"
 #include "mojo/public/cpp/application/application_connection.h"
@@ skipping 32 matching lines @@
     rect->height = 600;
     viewport_->Create(rect.Pass());
     viewport_->Show();
   }
 
   virtual void OnCreated(uint64_t native_viewport_id) MOJO_OVERRIDE {
     mojo::SizePtr size = mojo::Size::New();
     size->width = 800;
     size->height = 600;
     mojo::CommandBufferPtr command_buffer;
+    // TODO(jamesr): Output to a surface instead.
     gpu_service_->CreateOnscreenGLES2Context(
         native_viewport_id, size.Pass(), Get(&command_buffer));
     gles2_client_.reset(new GLES2ClientImpl(command_buffer.Pass()));
   }
 
   virtual void OnDestroyed() MOJO_OVERRIDE { mojo::RunLoop::current()->Quit(); }
 
   virtual void OnBoundsChanged(mojo::RectPtr bounds) MOJO_OVERRIDE {
     assert(bounds);
     mojo::SizePtr size(mojo::Size::New());
@@ skipping 18 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(SampleApp);
 };
 
 }  // namespace examples
 
 MojoResult MojoMain(MojoHandle shell_handle) {
   mojo::ApplicationRunner runner(new examples::SampleApp);
   return runner.Run(shell_handle);
 }