GitLab

- Moves setIcon from notification_builder_base to
notification_builder_mac as it is not shared between the builders.

- Adds setImagePath in unnotification_builder_mac to set the path of
the image that will be attached to the notification

Bug: 1136930
Change-Id: I9f5acfac73fc6dd738c4326d865059506e332ee0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2463828
Commit-Queue: Mohamed Adel <adelm@google.com>
Reviewed-by: Richard Knoll <knollr@chromium.org>
Reviewed-by: Rayan Kanso <rayankans@chromium.org>
Cr-Commit-Position: refs/heads/master@{#816963}