ozone: evdev: Drop unmapped key events

ui/events/ozone/evdev/keyboard_evdev.cc

Index: ui/events/ozone/evdev/keyboard_evdev.cc
diff --git a/ui/events/ozone/evdev/keyboard_evdev.cc b/ui/events/ozone/evdev/keyboard_evdev.cc
index 468f0fdf280bf184551b1835c68bffd34842dd54..b5a0849e0736a70e872db45f86e7ae0aa33039d7 100644
--- a/ui/events/ozone/evdev/keyboard_evdev.cc
+++ b/ui/events/ozone/evdev/keyboard_evdev.cc
@@ -228,6 +228,9 @@ void KeyboardEvdev::DispatchKey(unsigned int key, bool down) {
   ui::KeyboardCode code = KeyboardCodeFromEvdevKey(key);
   int flags = modifiers_->GetModifierFlags();
 
+  if (code == VKEY_UNKNOWN)
+    return;
+
   callback_.Run(make_scoped_ptr(new KeyEvent(
       down ? ET_KEY_PRESSED : ET_KEY_RELEASED,
       code,