Standardize usage of virtual/override/final in extensions/

extensions/renderer/render_view_observer_natives.cc

Index: extensions/renderer/render_view_observer_natives.cc
diff --git a/extensions/renderer/render_view_observer_natives.cc b/extensions/renderer/render_view_observer_natives.cc
index 1f2fb88cc0eb146d4512b768f20147dd2c3472b1..19a3974c1b8ad1743f77bbfd4061dd5fe139b5e9 100644
--- a/extensions/renderer/render_view_observer_natives.cc
+++ b/extensions/renderer/render_view_observer_natives.cc
@@ -23,13 +23,12 @@ class LoadWatcher : public content::RenderViewObserver {
               v8::Handle<v8::Function> cb)
       : content::RenderViewObserver(view), context_(context), callback_(cb) {}
 
-  virtual void DidCreateDocumentElement(blink::WebLocalFrame* frame) override {
+  void DidCreateDocumentElement(blink::WebLocalFrame* frame) override {
     CallbackAndDie(true);
   }
 
-  virtual void DidFailProvisionalLoad(blink::WebLocalFrame* frame,
-                                      const blink::WebURLError& error)
-      override {
+  void DidFailProvisionalLoad(blink::WebLocalFrame* frame,
+                              const blink::WebURLError& error) override {
     CallbackAndDie(false);
   }