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

content/browser/appcache/appcache_group.cc

Index: content/browser/appcache/appcache_group.cc
diff --git a/content/browser/appcache/appcache_group.cc b/content/browser/appcache/appcache_group.cc
index 50856700aa50f15e5ae9b27962df7abb78cfbb5e..7ebd2890ba4791fcef9c3a29a0ebeb569860c69a 100644
--- a/content/browser/appcache/appcache_group.cc
+++ b/content/browser/appcache/appcache_group.cc
@@ -27,8 +27,8 @@ class AppCacheGroup::HostObserver : public AppCacheHost::Observer {
   explicit HostObserver(AppCacheGroup* group) : group_(group) {}
 
   // Methods for AppCacheHost::Observer.
-  virtual void OnCacheSelectionComplete(AppCacheHost* host) override {}  // N/A
-  virtual void OnDestructionImminent(AppCacheHost* host) override {
+  void OnCacheSelectionComplete(AppCacheHost* host) override {}  // N/A
+  void OnDestructionImminent(AppCacheHost* host) override {
     group_->HostDestructionImminent(host);
   }
  private: