Update {virtual,override} to follow C++11 style in ppapi.

ppapi/proxy/flash_menu_resource.h

Index: ppapi/proxy/flash_menu_resource.h
diff --git a/ppapi/proxy/flash_menu_resource.h b/ppapi/proxy/flash_menu_resource.h
index 337e95332e8a933cf03ac6f5c0dd56135f6f345b..23b74876236034715a5a8302780b417b403d07bb 100644
--- a/ppapi/proxy/flash_menu_resource.h
+++ b/ppapi/proxy/flash_menu_resource.h
@@ -22,7 +22,7 @@ class FlashMenuResource
  public:
   // You must call Initialize after construction.
   FlashMenuResource(Connection connection, PP_Instance instance);
-  virtual ~FlashMenuResource();
+  ~FlashMenuResource() override;
 
   // Returns true on success. False means that this object can not be used.
   // This has to be separate from the constructor because the menu data could
@@ -30,16 +30,16 @@ class FlashMenuResource
   bool Initialize(const PP_Flash_Menu* menu_data);
 
   // Resource overrides.
-  virtual thunk::PPB_Flash_Menu_API* AsPPB_Flash_Menu_API() override;
+  thunk::PPB_Flash_Menu_API* AsPPB_Flash_Menu_API() override;
 
   // PPB_Flash_Menu_API.
-  virtual int32_t Show(const PP_Point* location,
-                       int32_t* selected_id,
-                       scoped_refptr<TrackedCallback> callback) override;
+  int32_t Show(const PP_Point* location,
+               int32_t* selected_id,
+               scoped_refptr<TrackedCallback> callback) override;
 
  private:
-  virtual void OnReplyReceived(const proxy::ResourceMessageReplyParams& params,
-                               const IPC::Message& msg) override;
+  void OnReplyReceived(const proxy::ResourceMessageReplyParams& params,
+                       const IPC::Message& msg) override;
 
   void OnShowReply(
       const proxy::ResourceMessageReplyParams& params,