[SfStats] Record vsync event connection count

Bug: 135480141
Test: ./statsd_testdrive 10062
Change-Id: I220f0c96935c96afea194ed8ca69922785cf296e
diff --git a/services/surfaceflinger/Scheduler/Scheduler.h b/services/surfaceflinger/Scheduler/Scheduler.h
index 01062f8..ccf61ed 100644
--- a/services/surfaceflinger/Scheduler/Scheduler.h
+++ b/services/surfaceflinger/Scheduler/Scheduler.h
@@ -144,6 +144,8 @@
     // Notifies the scheduler when the display size has changed. Called from SF's main thread
     void onPrimaryDisplayAreaChanged(uint32_t displayArea);
 
+    size_t getEventThreadConnectionCount(ConnectionHandle handle);
+
 private:
     friend class TestableScheduler;