Plumb resize notifications around sky/shell

sky/shell/ui/engine.h

 // Copyright 2015 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.
 
 #ifndef SKY_SHELL_UI_ENGINE_H_
 #define SKY_SHELL_UI_ENGINE_H_
 
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "sky/engine/public/web/WebFrameClient.h"
 #include "sky/engine/public/web/WebViewClient.h"
+#include "sky/shell/ui_delegate.h"
+#include "ui/gfx/geometry/size.h"
 
 namespace sky {
 namespace shell {
 class PlatformImpl;
 
-class Engine : public blink::WebFrameClient,
+class Engine : public UIDelegate,
+               public blink::WebFrameClient,
                public blink::WebViewClient {
  public:
   Engine();
   ~Engine() override;
 
   base::WeakPtr<Engine> GetWeakPtr();
 
   void Init();
 
+  void OnViewportMetricsChanged(const gfx::Size& size,
+                                float device_pixel_ratio) override;
+
  private:
   scoped_ptr<PlatformImpl> platform_impl_;
   blink::WebView* web_view_;
 
   base::WeakPtrFactory<Engine> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(Engine);
 };
 
 }  // namespace shell
 }  // namespace sky
 
 #endif  // SKY_SHELL_UI_ENGINE_H_