Fixing a race in KeyboardEventCounter::Reset.

BUG= 285279

Review URL: https://chromiumcodereview.appspot.com/23637005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@221259 0039d316-1c4b-4281-b951-d872f2087c98

media/base/keyboard_event_counter.cc

@@ -15,7 +15,8 @@ KeyboardEventCounter::~KeyboardEventCounter() {}
 
 void KeyboardEventCounter::Reset() {
   pressed_keys_.clear();
-  total_key_presses_ = 0;
+  base::subtle::NoBarrier_Store(
+      reinterpret_cast<base::subtle::AtomicWord*>(&total_key_presses_), 0);
 }
 
 void KeyboardEventCounter::OnKeyboardEvent(ui::EventType event,