GitLab

When user selects new custom background, use thumbnail from image
collections to fetche and calculate calculate the most frequent color on
the image. The calculated color is then stored in prefs with the rest of
the background info.

Bug: 874325
Change-Id: I5905b583f22174a491749543e922512e6b47caf0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1612235
Commit-Queue: Gayane Petrosyan <gayane@chromium.org>
Reviewed-by: Nicolas Ouellet-Payeur <nicolaso@chromium.org>
Reviewed-by: Gayane Petrosyan <gayane@chromium.org>
Reviewed-by: Kyle Milka <kmilka@chromium.org>
Cr-Commit-Position: refs/heads/master@{#660899}