Plumb resize notifications around sky/shell

sky/shell/ui/engine.h

Index: sky/shell/ui/engine.h
diff --git a/sky/shell/ui/engine.h b/sky/shell/ui/engine.h
index cba0c7a7ad9541e7f7c683af0cd8fbeb87b51101..9deccd8c6b8b4e2ddb0da4f8f3ebd062b65eacb9 100644
--- a/sky/shell/ui/engine.h
+++ b/sky/shell/ui/engine.h
@@ -10,12 +10,15 @@
 #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();
@@ -25,6 +28,9 @@ class Engine : public blink::WebFrameClient,
 
   void Init();
 
+  void OnViewportMetricsChanged(const gfx::Size& size,
+                                float device_pixel_ratio) override;
+
  private:
   scoped_ptr<PlatformImpl> platform_impl_;
   blink::WebView* web_view_;