[Ozone-Demo] Add support for NativeDisplayDelegate

ui/ozone/demo/gl_renderer.cc

 // Copyright 2014 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 "ui/ozone/demo/gl_renderer.h"
 
 #include "ui/gl/gl_bindings.h"
 #include "ui/gl/gl_context.h"
 #include "ui/gl/gl_surface.h"
 
@@ skipping 26 matching lines @@
     LOG(ERROR) << "Failed to make GL context current";
     return false;
   }
 
   return true;
 }
 
 void GlRenderer::RenderFrame() {
   float fraction = NextFraction();
 
+  context_->MakeCurrent(surface_.get());
+
   glViewport(0, 0, size_.width(), size_.height());
   glClearColor(1 - fraction, fraction, 0.0, 1.0);
   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 
   if (!surface_->SwapBuffers())
     LOG(FATAL) << "Failed to swap buffers";
 }
 
 }  // namespace ui