Standardize usage of virtual/override/final in chrome/browser/

chrome/browser/gpu/gl_string_manager.h

Index: chrome/browser/gpu/gl_string_manager.h
diff --git a/chrome/browser/gpu/gl_string_manager.h b/chrome/browser/gpu/gl_string_manager.h
index 254f1583961afa8d5febc1ecfd861c5b175c63d7..f9eb97eef491d9156dfc46920175d18b3a317faf 100644
--- a/chrome/browser/gpu/gl_string_manager.h
+++ b/chrome/browser/gpu/gl_string_manager.h
@@ -17,13 +17,13 @@ class GLStringManager : public content::GpuDataManagerObserver {
   static void RegisterPrefs(PrefRegistrySimple* registry);
 
   GLStringManager();
-  virtual ~GLStringManager();
+  ~GLStringManager() override;
 
   // Get cached GL strings in local state and send them to GpuDataManager.
   void Initialize();
 
   // content::GpuDataManagerObserver
-  virtual void OnGpuInfoUpdate() override;
+  void OnGpuInfoUpdate() override;
 
  private:
   std::string gl_vendor_;