Fix display:none issue for <webview>.

extensions/browser/guest_view/web_view/web_view_guest.cc

Index: extensions/browser/guest_view/web_view/web_view_guest.cc
diff --git a/extensions/browser/guest_view/web_view/web_view_guest.cc b/extensions/browser/guest_view/web_view/web_view_guest.cc
index fd7ac5b68f7ea26b4acdab4183d7e44897b4e2a2..76c353ccdcf98ba568ce100392e6f4e9bbfb5070 100644
--- a/extensions/browser/guest_view/web_view/web_view_guest.cc
+++ b/extensions/browser/guest_view/web_view/web_view_guest.cc
@@ -351,6 +351,10 @@ void WebViewGuest::WillDestroy() {
   if (!attached() && GetOpener())
     GetOpener()->pending_new_windows_.erase(this);
   DestroyUnattachedWindows();
+
+  scoped_ptr<base::DictionaryValue> args(new base::DictionaryValue());
+  DispatchEventToEmbedder(
+      new GuestViewBase::Event(webview::kEventPluginDestroyed, args.Pass()));
 }
 
 bool WebViewGuest::AddMessageToConsole(WebContents* source,