Factor common code into native_viewport_controller.cc

mojo/services/native_viewport/native_viewport_stub.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 "mojo/services/native_viewport/native_viewport.h"
 
 // Stub to build on platforms we don't fully support yet.
 
 namespace mojo {
 namespace services {
 
 class NativeViewportStub : public NativeViewport {
  public:
   NativeViewportStub(NativeViewportDelegate* delegate)
-      : delegate_(delegate) {
+      : NativeViewport(delegate) {
   }
   virtual ~NativeViewportStub() {
   }
 
  private:
   // Overridden from NativeViewport:
   virtual void Close() OVERRIDE {
     delegate_->OnDestroyed();
   }
 
-  NativeViewportDelegate* delegate_;
-
   DISALLOW_COPY_AND_ASSIGN(NativeViewportStub);
 };
 
 // static
 scoped_ptr<NativeViewport> NativeViewport::Create(
     shell::Context* context,
     NativeViewportDelegate* delegate) {
   return scoped_ptr<NativeViewport>(new NativeViewportStub(delegate)).Pass();
 }
 
 }  // namespace services
 }  // namespace mojo