Removes usage of Compositor/ContextFactory methods

mojo/aura/window_tree_host_mojo.cc

 // Copyright (c) 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 "mojo/aura/window_tree_host_mojo.h"
 
 #include "mojo/aura/context_factory_mojo.h"
 #include "mojo/public/c/gles2/gles2.h"
 #include "mojo/services/public/cpp/geometry/geometry_type_converters.h"
 #include "ui/aura/env.h"
@@ skipping 22 matching lines @@
       bounds_(bounds) {
   native_viewport_.set_client(this);
   native_viewport_->Create(Rect::From(bounds));
 
   MessagePipe pipe;
   native_viewport_->CreateGLES2Context(
       MakeRequest<CommandBuffer>(pipe.handle0.Pass()));
 
   // The ContextFactory must exist before any Compositors are created.
   if (context_factory_) {
-    ui::ContextFactory::SetInstance(NULL);
     delete context_factory_;
     context_factory_ = NULL;
   }
   context_factory_ = new ContextFactoryMojo(pipe.handle1.Pass());
-  ui::ContextFactory::SetInstance(context_factory_);
   aura::Env::GetInstance()->set_context_factory(context_factory_);
   CHECK(context_factory_) << "No GL bindings.";
 }
 
 WindowTreeHostMojo::~WindowTreeHostMojo() {
   DestroyCompositor();
   DestroyDispatcher();
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ skipping 107 matching lines @@
           event->flags, event->key_data->is_char);
       SendEventToProcessor(&ev);
       break;
     }
     // TODO(beng): touch, etc.
   }
   callback.Run();
 };
 
 }  // namespace mojo