Fix Accidently trigger A11y button long pressed

We used the original down location while injecting all down events.
It accidently increases the velocity in the beginning and cause
Launcher detect the wrong gesture.

To fix it, we adjust the down time to real downTime.
Test: manually test
Bug: 165896230

Change-Id: I318dbc2af04298a21b9efe99278285911f56b1a0