GitLab

Add support for image, list, and progress notifications. This
involves serializing the RichNotificationData structure.

Move some existing crosapi::Bitmap serialization code into a
shared utility file. Add deserialization to SkBitmap. For now
the image format is hard-coded. crbug.com/1116652 tracks more
flexible image serialization.

Add unit tests for both ash side and lacros side.

Bug: 1113889
Test: unit_tests, manual with Notifications Galore chrome app

Change-Id: I27b1c74f828751f35d845e625052386530de9722
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2357749
Commit-Queue: James Cook <jamescook@chromium.org>
Reviewed-by: Jun Mukai <mukai@chromium.org>
Reviewed-by: Greg Kerr <kerrnel@chromium.org>
Reviewed-by: Darin Fisher <darin@chromium.org>
Reviewed-by: Erik Chen <erikchen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#799386}