replace 'virtual ... OVERRIDE' with '... override'

base/synchronization/waitable_event_posix.cc

Index: base/synchronization/waitable_event_posix.cc
diff --git a/base/synchronization/waitable_event_posix.cc b/base/synchronization/waitable_event_posix.cc
index 89f42fff2f7d6f9a84d6be5d3923bdc169d5756f..696ffc7a02abe5a1c21e429032b217fd7f142c91 100644
--- a/base/synchronization/waitable_event_posix.cc
+++ b/base/synchronization/waitable_event_posix.cc
@@ -91,7 +91,7 @@ class SyncWaiter : public WaitableEvent::Waiter {
         cv_(&lock_) {
   }
 
-  virtual bool Fire(WaitableEvent* signaling_event) OVERRIDE {
+  bool Fire(WaitableEvent* signaling_event) override {
     base::AutoLock locked(lock_);
 
     if (fired_)
@@ -117,9 +117,7 @@ class SyncWaiter : public WaitableEvent::Waiter {
   // These waiters are always stack allocated and don't delete themselves. Thus
   // there's no problem and the ABA tag is the same as the object pointer.
   // ---------------------------------------------------------------------------
-  virtual bool Compare(void* tag) OVERRIDE {
-    return this == tag;
-  }
+  bool Compare(void* tag) override { return this == tag; }
 
   // ---------------------------------------------------------------------------
   // Called with lock held.