SF: VSyncReactor add period modification functions

Adds 2 more functions from the DispSync interface to VSyncReactor,
{get,set}Period

Bug: 140303479
Test: 2 new units

Change-Id: Ie0084597c80d6d43099201fb49b71ae9badea3ee
diff --git a/services/surfaceflinger/Scheduler/VSyncReactor.cpp b/services/surfaceflinger/Scheduler/VSyncReactor.cpp
index 9ce440c..6588d1b 100644
--- a/services/surfaceflinger/Scheduler/VSyncReactor.cpp
+++ b/services/surfaceflinger/Scheduler/VSyncReactor.cpp
@@ -87,4 +87,12 @@
     return mTracker->nextAnticipatedVSyncTimeFrom(mClock->now());
 }
 
+void VSyncReactor::setPeriod(nsecs_t period) {
+    mTracker->setPeriod(period);
+}
+
+nsecs_t VSyncReactor::getPeriod() {
+    return mTracker->currentPeriod();
+}
+
 } // namespace android::scheduler