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

ppapi/proxy/browser_font_singleton_resource.h

Index: ppapi/proxy/browser_font_singleton_resource.h
diff --git a/ppapi/proxy/browser_font_singleton_resource.h b/ppapi/proxy/browser_font_singleton_resource.h
index 85e2dc6edc7b663f9eaa0fc935cf2a2a741621af..ddbb690a638f63d668f5ba11c79af56c47c3cb1a 100644
--- a/ppapi/proxy/browser_font_singleton_resource.h
+++ b/ppapi/proxy/browser_font_singleton_resource.h
@@ -19,14 +19,14 @@ class BrowserFontSingletonResource
       public thunk::PPB_BrowserFont_Singleton_API {
  public:
   BrowserFontSingletonResource(Connection connection, PP_Instance instance);
-  virtual ~BrowserFontSingletonResource();
+  ~BrowserFontSingletonResource() override;
 
   // Resource override.
-  virtual thunk::PPB_BrowserFont_Singleton_API*
+  thunk::PPB_BrowserFont_Singleton_API*
       AsPPB_BrowserFont_Singleton_API() override;
 
   // thunk::PPB_BrowserFontSingleton_API implementation.
-  virtual PP_Var GetFontFamilies(PP_Instance instance) override;
+  PP_Var GetFontFamilies(PP_Instance instance) override;
 
  private:
   // Lazily-filled-in list of font families.