GitLab

Per latest designs from UX, move to the 3 line format provided by the
Notification Center, remove all multi-line notification data, and always
use the first profile image photo instead of the app icon for multiple
senders.

BUG=281520

Review URL: https://chromiumcodereview.appspot.com/23981004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@222157 0039d316-1c4b-4281-b951-d872f2087c98