cancel overlay-scrollbar hover state when moving pointer out of window for ChromeOS

ui/events/blink/web_input_event.cc

Index: ui/events/blink/web_input_event.cc
diff --git a/ui/events/blink/web_input_event.cc b/ui/events/blink/web_input_event.cc
index 705818f15fa968173113e6cfdb55a2c9b97233de..674f64f24e4a0eafe525f43565331fca9c1e733f 100644
--- a/ui/events/blink/web_input_event.cc
+++ b/ui/events/blink/web_input_event.cc
@@ -399,8 +399,14 @@ blink::WebMouseEvent MakeWebMouseEventFromUiEvent(const MouseEvent& event) {
       webkit_event.type = blink::WebInputEvent::MouseUp;
       webkit_event.clickCount = event.GetClickCount();
       break;
-    case ET_MOUSE_ENTERED:
     case ET_MOUSE_EXITED:
+// TODO(chaopeng) this fix only for chromeos now, should convert ET_MOUSE_EXITED
+// to MouseLeave when crbug.com/450631 fixed.
+#if defined(OS_CHROMEOS)

[aelias_OOO_until_Jul13, 2016/10/07 02:09:51]

Platform ifdefs are generally a bad practice, how hard is it to fix
crbug.com/450631 or otherwise avoid an ifdef here?

[dtapuska, 2016/10/07 14:30:39]

aelias@ completely agree this ifdef is bad. We do need to fix 450631 and we are
pushing lanwei to ensure that is done soon. But the ifdef is needed to unblock
this bug and it is reasonable to do this ifdef instead of other work arounds.

[aelias_OOO_until_Jul13, 2016/10/07 16:26:19]

OK, fine since you're actively working on the fix.

+      webkit_event.type = blink::WebInputEvent::MouseLeave;
+      break;
+#endif
+    case ET_MOUSE_ENTERED:
     case ET_MOUSE_MOVED:
     case ET_MOUSE_DRAGGED:
       webkit_event.type = blink::WebInputEvent::MouseMove;