GitLab

Added a flag to EndPositionStrategy which allows it to prioritize the
previously snapped targets when finding a snap point. If no target is
found then it defaults to finding the closest snap point as it does
normally. Also added unit tests.

This is currently not used, but will be used in a follow-up patch for
resnapping the container when layout changes occur.

Bug: 866127
Change-Id: I9c8d6db608a5219f4178afe0a79136b81cfb3378
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1929644
Commit-Queue: Kaan Alsan <alsan@google.com>
Reviewed-by: Majid Valipour <majidvp@chromium.org>
Reviewed-by: Yi Gu <yigu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#718274}