diff --git a/services/surfaceflinger/SurfaceFlinger.h b/services/surfaceflinger/SurfaceFlinger.h
index f1c19c2..353e7ba 100644
--- a/services/surfaceflinger/SurfaceFlinger.h
+++ b/services/surfaceflinger/SurfaceFlinger.h
@@ -383,8 +383,8 @@
      * VSync
      */
      void enableHardwareVsync();
-     void disableHardwareVsync();
-     void resyncToHardwareVsync();
+     void disableHardwareVsync(bool makeUnavailable);
+     void resyncToHardwareVsync(bool makeAvailable);
 
     /* ------------------------------------------------------------------------
      * Debugging & dumpsys
@@ -467,6 +467,7 @@
     // protected by mHWVsyncLock
     Mutex mHWVsyncLock;
     bool mPrimaryHWVsyncEnabled;
+    bool mHWVsyncAvailable;
 
     /* ------------------------------------------------------------------------
      * Feature prototyping