Fix up some event handling in MacOS

Bug: skia:
Change-Id: I46a1526cb6622c0ff04dbee9f64febca388f3571
Reviewed-on: https://skia-review.googlesource.com/c/187927
Commit-Queue: Mike Reed <reed@google.com>
Reviewed-by: Mike Reed <reed@google.com>
3 files changed