Update notification dots in Taskbar All Apps.

AllAppsStore already has the business logic for this, we just were not
piping along to it.

Test: Dismiss notification from tray while All Apps is open, and dot
should go away in All Apps.
Fix: 277925243

Change-Id: I29c5723fd77d22f683f5518bd6e2e3206ddee999
2 files changed