Add --use-more-webui runtime flag to toggle WebUI replacements for native dialogs.

chrome/browser/ui/webui/hung_renderer_dialog.h

Index: chrome/browser/ui/webui/hung_renderer_dialog.h
diff --git a/chrome/browser/ui/webui/hung_renderer_dialog.h b/chrome/browser/ui/webui/hung_renderer_dialog.h
index aa9eebc5e5fa499fd990664ec3a77d5dd3bf0ca0..e26a8a13a4a92d438076b05fd3ac9b31c4f8cc3d 100644
--- a/chrome/browser/ui/webui/hung_renderer_dialog.h
+++ b/chrome/browser/ui/webui/hung_renderer_dialog.h
@@ -15,6 +15,7 @@
 #include "ui/gfx/native_widget_types.h"
 
 class TabContents;
+class HungRendererDialogHandler;
 
 class HungRendererDialog : private HtmlDialogUIDelegate {
  public:
@@ -49,6 +50,9 @@ class HungRendererDialog : private HtmlDialogUIDelegate {
   // The tab contents.
   TabContents* contents_;
 
+  // The dialog handler.
+  HungRendererDialogHandler* handler_;
+
   // The dialog window.
   gfx::NativeWindow window_;
 
@@ -61,6 +65,8 @@ class HungRendererDialogHandler : public WebUIMessageHandler {
  public:
   explicit HungRendererDialogHandler(TabContents* contents);
 
+  void CloseDialog();
+
   // Overridden from WebUIMessageHandler
   virtual void RegisterMessages();