Add unit test for toolbars' force touch gestures

This CL adds a unit test for the force touch gesture recognizer added
to the toolbar buttons, triggering the popup menu.

Bug: 864430
Cq-Include-Trybots: luci.chromium.try:ios-simulator-full-configs;master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: Icc2524f7e8e58bf20fb4b1381913cb82c57206a8
Reviewed-on: https://chromium-review.googlesource.com/1150142
Reviewed-by: Mark Cogan <marq@chromium.org>
Commit-Queue: Gauthier Ambard <gambard@chromium.org>
Cr-Commit-Position: refs/heads/master@{#578349}
5 files changed