SurfaceFlinger: add VSYNC-predicted as debug option

Add a trace point for the predicted VSYNC event.
This is controlled by debug.sf.show_predicted_vsync (default off)

Fixes: 150414668
Test: adb shell stop && adb shell setprop debug.sf.show_predicted_vsync 1 && adb shell start
Change-Id: Idd140dd2cb98c6bdd25197a742084cd5d4debd90
2 files changed