Some fixes for black screen when pressing home button

Pressing home button sometimes involves a rotation (eg. when app is
running in landscape mode but launch is fixed portrait mode). This will
trigger a screen freeze, which clears the transition. We still need to
add the opening app to the opening list even if transition is unset,
otherwise it doesn't wait for app to draw first frame.

Also during rotation, app, launcher and wallpaper all get relaunched.
The transition can't start until the first frame on the new launcher
window comes back. We can't start it based on the draw state of the old
window, because the old window could get removed and readded shortly
after we start the transition, and it shows up as a black frame.

bug: 27391256
bug: 27295820
Change-Id: I346685076657eef209d0fab68f272e218b55e011