Prevent dismissing starting window when reopening app

We reset the draw state in case the app was hidden before. This
ensures that the starting window doesn't get dismissed
immediately, in case there is some weirdness going on when
restarting an activity, like a surface view that hasn't drawn yet.

However, we don't reset draw state for starting windows as the
snapshot doesn't redraw ever.

Test: Open Chrome, swipe up, reopen Chrome, ensure no holes
Test: Same for camera
Test: go/wm-smoke
Fixes: 134561008
Change-Id: I02742cef93a6b58f2096c98514371119fa606d16