The test selects the first photo, scrolls to the bottom and back up
to the top to make sure the selection border is active and of correct
size (old bug I encountered once).

This should also function as a regression test for bugs like the one
seen in issue 1051523 (where a white circle got overlaid on top of
all photos).

Bug: 1051523, 656015
Change-Id: Ifb119c5e9450be5ef06b303eb3549315c0e4a623
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2083178
Commit-Queue: Finnur Thorarinsson <finnur@chromium.org>
Reviewed-by: Boris Sazonov <bsazonov@chromium.org>
Cr-Commit-Position: refs/heads/master@{#747188}