Avoid drawing the first frame in launcher before animation completes

Currently Launcher reports the drawing of the first frame before the
fade-in animation runs to a completion. This CL pauses the pre-draw
until the animation concludes so that the performance metrics matches
what user actually sees.

Bug: 210527498
Test: 1) reboot verify things works 2) sign in to second user, verify
things works.

Change-Id: I0146c0408005c3de75098b9401089ed2bcbcb6d6
1 file changed