Update some of the share sheet styling to match the spec. Also add
in the icons for STTS and QRCodes.

screenshot: http://screen/4okyHGgCLAn.png

Bug: 1009124
Change-Id: If1aa78812644602643ff5d76d068ad1151bd159e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1949077Reviewed-by: David Trainor <dtrainor@chromium.org>
Reviewed-by: Jeffrey Cohen <jeffreycohen@chromium.org>
Reviewed-by: Matthew Jones <mdjones@chromium.org>
Commit-Queue: Kyle Milka <kmilka@chromium.org>
Cr-Commit-Position: refs/heads/master@{#721700}