Standardize usage of virtual/override/final in extensions/

extensions/renderer/resource_bundle_source_map.h

Index: extensions/renderer/resource_bundle_source_map.h
diff --git a/extensions/renderer/resource_bundle_source_map.h b/extensions/renderer/resource_bundle_source_map.h
index 84a5411964ccf8826f93aeb0835f8477b0b4df56..098786106bffe13b71255aaa04fd75a59d0ec2bb 100644
--- a/extensions/renderer/resource_bundle_source_map.h
+++ b/extensions/renderer/resource_bundle_source_map.h
@@ -24,11 +24,11 @@ namespace extensions {
 class ResourceBundleSourceMap : public extensions::ModuleSystem::SourceMap {
  public:
   explicit ResourceBundleSourceMap(const ui::ResourceBundle* resource_bundle);
-  virtual ~ResourceBundleSourceMap();
+  ~ResourceBundleSourceMap() override;
 
-  virtual v8::Handle<v8::Value> GetSource(v8::Isolate* isolate,
-                                          const std::string& name) override;
-  virtual bool Contains(const std::string& name) override;
+  v8::Handle<v8::Value> GetSource(v8::Isolate* isolate,
+                                  const std::string& name) override;
+  bool Contains(const std::string& name) override;
 
   void RegisterSource(const std::string& name, int resource_id);