Enable Shadow DOM and scoped stylesheet for extensions and Web UI.

chrome/renderer/chrome_render_view_observer.h

Index: chrome/renderer/chrome_render_view_observer.h
diff --git a/chrome/renderer/chrome_render_view_observer.h b/chrome/renderer/chrome_render_view_observer.h
index 923e0067ce4b8a312a955749e508f06dc38ad176..9ba86ca59b11f33c284de504afcf4d081cc64a3f 100644
--- a/chrome/renderer/chrome_render_view_observer.h
+++ b/chrome/renderer/chrome_render_view_observer.h
@@ -104,6 +104,7 @@ class ChromeRenderViewObserver : public content::RenderViewObserver,
                                       bool default_value) OVERRIDE;
   virtual bool allowWriteToClipboard(WebKit::WebFrame* frame,
                                      bool default_value) OVERRIDE;
+  virtual bool allowWebComponents(const WebKit::WebDocument&, bool) OVERRIDE;
   virtual void didNotAllowPlugins(WebKit::WebFrame* frame) OVERRIDE;
   virtual void didNotAllowScript(WebKit::WebFrame* frame) OVERRIDE;
   virtual bool allowDisplayingInsecureContent(
@@ -182,6 +183,9 @@ class ChromeRenderViewObserver : public content::RenderViewObserver,
   // Determines if a host is in the strict security host set.
   bool IsStrictSecurityHost(const std::string& host);
 
+  // Determines if the document has a permission to use experimental Web API
+  bool IsExperimentalWebFeatureAllowed(const WebKit::WebDocument& document);
+
   // Save the JavaScript to preload if a ViewMsg_WebUIJavaScript is received.
   scoped_ptr<WebUIJavaScript> webui_javascript_;