Mojo: MOJO_OVERRIDE -> override in mojo/.

mojo/public/python/src/python_system_helper.cc

Index: mojo/public/python/src/python_system_helper.cc
diff --git a/mojo/public/python/src/python_system_helper.cc b/mojo/public/python/src/python_system_helper.cc
index 065ea24965b5f304de7bc5fca06b7b15fdb14676..f42e671b0aacf8ea6f7a184dae659f44b1825be2 100644
--- a/mojo/public/python/src/python_system_helper.cc
+++ b/mojo/public/python/src/python_system_helper.cc
@@ -37,7 +37,7 @@ class PythonClosure : public mojo::Closure::Runnable {
     Py_DECREF(callable_);
   }
 
-  virtual void Run() const MOJO_OVERRIDE {
+  virtual void Run() const override {
     ScopedGIL acquire_gil;
     PyObject* empty_tuple = PyTuple_New(0);
     if (!empty_tuple) {
@@ -90,7 +90,7 @@ class PythonAsyncWaiter::AsyncWaiterRunnable
 
   void set_wait_id(int wait_id) { wait_id_ = wait_id; }
 
-  virtual void Run(MojoResult mojo_result) const MOJO_OVERRIDE {
+  virtual void Run(MojoResult mojo_result) const override {
     MOJO_DCHECK(wait_id_);
 
     // Remove to reference to this object from PythonAsyncWaiter and ensure this