surfaceflinger: put RefreshRateOverlay in the center for circular displays

- Use debug.sf.show_refresh_rate_overlay_in_middle sysprop to turn on.

Test: Visual
Before: screenshot/3nJHsbGsXAjLWNr
After: screenshot/3RtYGnCAe5M2Pf9

Bug: 265356373
Change-Id: Ib598e6f5c7a1c4b13fa4d6e4dbc2e29b2e25bfc8
diff --git a/services/surfaceflinger/SurfaceFlinger.h b/services/surfaceflinger/SurfaceFlinger.h
index 37aa3d5..064a1f1 100644
--- a/services/surfaceflinger/SurfaceFlinger.h
+++ b/services/surfaceflinger/SurfaceFlinger.h
@@ -653,6 +653,8 @@
     bool mRefreshRateOverlaySpinner = false;
     // Show render rate with refresh rate overlay
     bool mRefreshRateOverlayRenderRate = false;
+    // Show render rate overlay offseted to the middle of the screen (e.g. for circular displays)
+    bool mRefreshRateOverlayShowInMiddle = false;
 
     void setDesiredActiveMode(display::DisplayModeRequest&&, bool force = false)
             REQUIRES(mStateLock);