Fix the Windows implementation of EventGenerator::PressKey().

ui/aura/test/event_generator.h

Index: ui/aura/test/event_generator.h
diff --git a/ui/aura/test/event_generator.h b/ui/aura/test/event_generator.h
index 80b83b18749a59af288b3d1e7e4c2e79bba54155..61893c78ccf7e64cf45ae358c7e33ebbb6a6a821 100644
--- a/ui/aura/test/event_generator.h
+++ b/ui/aura/test/event_generator.h
@@ -94,12 +94,14 @@ class EventGenerator {
   void PressMoveAndReleaseTouchToCenterOf(Window* window);
 
   // Generates a key press event. On platforms except Windows and X11, a key
-  // event without native_event() is generated.
+  // event without native_event() is generated. Note that ui::EF_ flags should
+  // be passed as |flags|, not the native ones like 'ShiftMask' in <X11/X.h>.
   // TODO(yusukes): Support native_event() on all platforms.
   void PressKey(ui::KeyboardCode key_code, int flags);
 
   // Generates a key release event. On platforms except Windows and X11, a key
-  // event without native_event() is generated.
+  // event without native_event() is generated. Note that ui::EF_ flags should
+  // be passed as |flags|, not the native ones like 'ShiftMask' in <X11/X.h>.
   // TODO(yusukes): Support native_event() on all platforms.
   void ReleaseKey(ui::KeyboardCode key_code, int flags);