mCurrentShift is based on displacement, but is used and set in different
places. To keep consistency throughout, we should override the
displacement at the source instead.
Test: manually swiped up between home/overview threshold and catch up
threshold; let go to go to overview and ensure no jump occurs.
Flag: teamfood (ENABLE_TRANSIENT_TASKBAR)
Fixes: 259981285
Change-Id: Id9f5b2bcdc2e56e15ddb6d93c4ee5d5ececc094d
Tony Wickham
7a19cccafe