Add input event observer to generate stack trace in flakey test.

This CL temporarily adds an InputEventObserver for TouchMoves on
RenderWidgetHost to try and detect the source of spurious TouchMove
events in the Windows flakes of
SitePerProcessEmulatedTouchBrowserTest.EmulatedTouchShowPressHasTouchID.

Bug: 833380
Change-Id: Ia3d6f75013acbbc9ed1a823c799741e2c64d2253
Reviewed-on: https://chromium-review.googlesource.com/1188876
Reviewed-by: Ken Buchanan <kenrb@chromium.org>
Commit-Queue: James MacLean <wjmaclean@chromium.org>
Cr-Commit-Position: refs/heads/master@{#586018}
1 file changed