Add some visual documentation for the ShelfView

This doesn't change any behavior and only explains the current behavior.

Bug: 805612
Change-Id: I022407502560b92b979310c6685563a1cbde0ce9
Reviewed-on: https://chromium-review.googlesource.com/1150407
Reviewed-by: Michael Wasserman <msw@chromium.org>
Commit-Queue: Manu Cornet <manucornet@chromium.org>
Cr-Commit-Position: refs/heads/master@{#578031}
1 file changed