Make SkyView vs. WebView controlable via url path

sky/shell/ui/engine.cc

Index: sky/shell/ui/engine.cc
diff --git a/sky/shell/ui/engine.cc b/sky/shell/ui/engine.cc
index b16d44e67338461efc034d8f117a01bc1cf2e174..e3df08d99b701ea473dff315faa9341908705e36 100644
--- a/sky/shell/ui/engine.cc
+++ b/sky/shell/ui/engine.cc
@@ -171,13 +171,14 @@ void Engine::OnInputEvent(InputEventPtr event) {
 }
 
 void Engine::LoadURL(const mojo::String& url) {
-  // Enable SkyView here.
-  if (false) {
+  if (!WebView::shouldUseWebView(responseURL)) {
     sky_view_ = blink::SkyView::Create(this);
     sky_view_->Load(GURL(url));
     return;
   }
 
+  LOG(WARNING) << ".sky support is deprecated, please use .dart for main()";
+
   // Something bad happens if you try to call WebView::close and replace
   // the webview.  So for now we just load into the existing one. :/
   if (!web_view_)