base

Show toast for non-resizeble docked task under the task itself

Move the show toast code to WM, so that we can schedule to show the
toast when the app becomes visible. Otherwise the toast always shows
up a long time before the app itself.

bug: 25433902
bug: 25873338

Change-Id: I879f8e0570829934fac806c2861bda9f65e08969