Support webview tag when the container extension is embedded in a webUI

content/renderer/browser_plugin/browser_plugin.cc

Index: content/renderer/browser_plugin/browser_plugin.cc
diff --git a/content/renderer/browser_plugin/browser_plugin.cc b/content/renderer/browser_plugin/browser_plugin.cc
index c80b8c74c5de1ec732410a8bc9d2fef11bf84d35..a0c8c75c2e28d506349de859945de525fbf5b93b 100644
--- a/content/renderer/browser_plugin/browser_plugin.cc
+++ b/content/renderer/browser_plugin/browser_plugin.cc
@@ -89,6 +89,7 @@ BrowserPlugin::BrowserPlugin(
       before_first_navigation_(true),
       mouse_locked_(false),
       browser_plugin_manager_(render_view->GetBrowserPluginManager()),
+      embedder_frame_url_(frame->document().url()),
       compositing_enabled_(false),
       weak_ptr_factory_(this) {
 }
@@ -374,6 +375,7 @@ void BrowserPlugin::Attach(scoped_ptr<base::DictionaryValue> extra_params) {
   attach_params.storage_partition_id = storage_partition_id_;
   attach_params.persist_storage = persist_storage_;
   attach_params.src = GetSrcAttribute();
+  attach_params.embedder_frame_url = embedder_frame_url_.spec();
   GetDamageBufferWithSizeParams(&attach_params.auto_size_params,
                                 &attach_params.resize_guest_params,
                                 false);