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

chrome/renderer/extensions/extension_dispatcher.cc

Index: chrome/renderer/extensions/extension_dispatcher.cc
diff --git a/chrome/renderer/extensions/extension_dispatcher.cc b/chrome/renderer/extensions/extension_dispatcher.cc
index 1d9625993911aa549914e7fe21c966e7370c2e5a..5fc2a2d79b89fde57e372799180bcaeff109ad2e 100644
--- a/chrome/renderer/extensions/extension_dispatcher.cc
+++ b/chrome/renderer/extensions/extension_dispatcher.cc
@@ -51,6 +51,7 @@
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebDataSource.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebDocument.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebFrame.h"
+#include "third_party/WebKit/Source/WebKit/chromium/public/WebRuntimeFeatures.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebScopedUserGesture.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebSecurityPolicy.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebView.h"
@@ -257,6 +258,13 @@ void ExtensionDispatcher::WebKitInitialized() {
     forced_idle_timer_.Start(FROM_HERE,
         base::TimeDelta::FromMilliseconds(kMaxExtensionIdleHandlerDelayMs),
         RenderThread::Get(), &RenderThread::IdleHandler);
+    // Enables shadow DOM and scoped stylesheet only for extensions.
+    // This allows extension developes to try thiese features without

[Aaron Boodman, 2012/05/15 18:30:56]

typo: these

+    // worrying about flag settings and to keep these hidden from the
+    // wild Web at the same time. This should be eventually removed
+    // once these feature is enabled by default.
+    WebKit::WebRuntimeFeatures::enableShadowDOM(true);

[Aaron Boodman, 2012/05/15 18:30:56]

A static flag is not going to be sufficient. A single process can host both
extension and non-extension WebViews.

Take a look at extension_webkit_preferences.cc for an example of how other
WebKit runtime flags are switched on.

+    WebKit::WebRuntimeFeatures::enableStyleScoped(true);
   }
 
   // Initialize host permissions for any extensions that were activated before