🦁Fix popup in showcase after introducing layout guides

The layout guides were not set up in showcase, so the popup was broken.

This also fixes a autolayout warning when the second text view was
larger than one line. The stack view didn't know which text view to
shrink if necessary.

This also turns on adjusting content insets due to safe area for the
popup view controller, so the bottom of the popup does respect the
safe area.

Bug: 962957
Change-Id: I626fcb40420f8728094760cb1261766899e82df9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1611823
Reviewed-by: Rohit Rao <rohitrao@chromium.org>
Reviewed-by: edchin <edchin@chromium.org>
Commit-Queue: Robbie Gibson <rkgibson@google.com>
Cr-Commit-Position: refs/heads/master@{#662603}
5 files changed