Add touch support to viewer

Bug: skia:8737
Change-Id: I81379bd57684626705da48e03c91b83e91031e0b
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/239104
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>
1 file changed