Android: Fix a bug not supporting gamepad

https://crrev.com/c/1135874 left out checking gamepad events
by mistake. This CL fixes it by adding the check against
GenericMotionEvent in the content ui event handler.

Tested on https://html5gamepad.com with a USB gamepad.

Bug: 906347
Change-Id: I2bd0890f2533e70a772dbb0b005d69bf086d1595
Reviewed-on: https://chromium-review.googlesource.com/c/1356727
Reviewed-by: Bo <boliu@chromium.org>
Commit-Queue: Jinsuk Kim <jinsukkim@chromium.org>
Cr-Commit-Position: refs/heads/master@{#613268}
2 files changed