Teach SkyView path to draw a circle

sky/engine/bindings/builtin_sky.h

Index: sky/engine/bindings/builtin_sky.h
diff --git a/sky/engine/bindings/builtin_sky.h b/sky/engine/bindings/builtin_sky.h
index 1fd2078920ffb298c56d635d5c2f09441e0119e7..cbeb54c89068fa7aa8447a8d1e7789c452e817d5 100644
--- a/sky/engine/bindings/builtin_sky.h
+++ b/sky/engine/bindings/builtin_sky.h
@@ -12,6 +12,7 @@
 
 namespace blink {
 class DOMDartState;
+class View;
 
 class BuiltinSky : public DartClassProvider {
  public:
@@ -19,6 +20,7 @@ class BuiltinSky : public DartClassProvider {
   ~BuiltinSky();
 
   void InstallWindow(DOMDartState* dart_state);
+  void InstallView(View* view);
 
   // DartClassProvider:
   Dart_Handle GetClassByName(const char* class_name) override;