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

ppapi/proxy/ppp_instance_private_proxy_unittest.cc

Index: ppapi/proxy/ppp_instance_private_proxy_unittest.cc
diff --git a/ppapi/proxy/ppp_instance_private_proxy_unittest.cc b/ppapi/proxy/ppp_instance_private_proxy_unittest.cc
index e373c48d2e843f1aa8bd5eab60cc5511b1873673..8b758d9084fb85021d750fb5380e1a8fd2f6ac8c 100644
--- a/ppapi/proxy/ppp_instance_private_proxy_unittest.cc
+++ b/ppapi/proxy/ppp_instance_private_proxy_unittest.cc
@@ -25,11 +25,11 @@ namespace ppapi {
 class V8ObjectVar : public ppapi::Var {
  public:
   V8ObjectVar() {}
-  virtual ~V8ObjectVar() {}
+  ~V8ObjectVar() override {}
 
   // Var overrides.
-  virtual V8ObjectVar* AsV8ObjectVar() override { return this; }
-  virtual PP_VarType GetType() const override { return PP_VARTYPE_OBJECT; }
+  V8ObjectVar* AsV8ObjectVar() override { return this; }
+  PP_VarType GetType() const override { return PP_VARTYPE_OBJECT; }
 };
 
 namespace proxy {