SurfaceFlinger: give SF its own vsync phase

This change allows SurfaceFlinger to run at a different vsync phase offset from
that used by external listeners.

Bug: 11175503
Change-Id: I561c53a5659fa6dc1e3e4ae30340f3c1a6adceb4
diff --git a/services/surfaceflinger/SurfaceFlinger.h b/services/surfaceflinger/SurfaceFlinger.h
index 03c4ba3..f08e66a 100644
--- a/services/surfaceflinger/SurfaceFlinger.h
+++ b/services/surfaceflinger/SurfaceFlinger.h
@@ -428,6 +428,7 @@
     nsecs_t mBootTime;
     bool mGpuToCpuSupported;
     sp<EventThread> mEventThread;
+    sp<EventThread> mSFEventThread;
     sp<EventControlThread> mEventControlThread;
     EGLContext mEGLContext;
     EGLConfig mEGLConfig;