Teach SkyShell how to listen for VIEW intents of sky: urls.

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 1aafbb39f4a5004bfa8d57a856405351f8c105d1..bdf6d043162a056dd9a6a14783de990bb1b544e7 100644
--- a/sky/shell/ui/engine.h
+++ b/sky/shell/ui/engine.h
@@ -53,11 +53,14 @@ class Engine : public UIDelegate,
   void OnViewportMetricsChanged(int width, int height,
                                 float device_pixel_ratio) override;
   void OnInputEvent(InputEventPtr event) override;
+  void LoadURL(const mojo::String& url) override;
 
   // WebViewClient methods:
   void initializeLayerTreeView() override;
   void scheduleVisualUpdate() override;
 
+  void UpdateWebViewSize();
+
   scoped_ptr<PlatformImpl> platform_impl_;
   scoped_ptr<Animator> animator_;
   blink::WebView* web_view_;