Standardize usage of virtual/override/final in extensions/

extensions/browser/guest_view/guest_view_manager.h

Index: extensions/browser/guest_view/guest_view_manager.h
diff --git a/extensions/browser/guest_view/guest_view_manager.h b/extensions/browser/guest_view/guest_view_manager.h
index db13e7c98318fb9c46ec1d724a3d448f80ad6180..722b984183b4eb78a719c86b7fadf8660000d14c 100644
--- a/extensions/browser/guest_view/guest_view_manager.h
+++ b/extensions/browser/guest_view/guest_view_manager.h
@@ -29,7 +29,7 @@ class GuestViewManager : public content::BrowserPluginGuestManager,
                          public base::SupportsUserData::Data {
  public:
   explicit GuestViewManager(content::BrowserContext* context);
-  virtual ~GuestViewManager();
+  ~GuestViewManager() override;
 
   static GuestViewManager* FromBrowserContext(content::BrowserContext* context);
 
@@ -79,11 +79,12 @@ class GuestViewManager : public content::BrowserPluginGuestManager,
       const GURL& guest_site);
 
   // BrowserPluginGuestManager implementation.
-  virtual content::WebContents* GetGuestByInstanceID(
+  content::WebContents* GetGuestByInstanceID(
       content::WebContents* embedder_web_contents,
       int element_instance_id) override;
-  virtual bool ForEachGuest(content::WebContents* embedder_web_contents,
-                            const GuestCallback& callback) override;
+  bool ForEachGuest(content::WebContents* embedder_web_contents,
+                    const GuestCallback& callback) override;
+
  protected:
   friend class GuestViewBase;
   FRIEND_TEST_ALL_PREFIXES(GuestViewManagerTest, AddRemove);