Support SurfaceView synchronization.

Add API for fetching the next frame number to be produced by
a given buffer producer. Add an API to SurfaceComposer to 
defer execution of the current transaction until a given frame number. 
Together these may be used to synchronize app drawing and surface 
control updates.

Change-Id: I8e0f4993332ac0199c768c88581a453fefbaff1d
diff --git a/services/surfaceflinger/MonitoredProducer.cpp b/services/surfaceflinger/MonitoredProducer.cpp
index 79ef92f..68b6b86 100644
--- a/services/surfaceflinger/MonitoredProducer.cpp
+++ b/services/surfaceflinger/MonitoredProducer.cpp
@@ -127,6 +127,10 @@
     return mProducer->getConsumerName();
 }
 
+uint64_t MonitoredProducer::getNextFrameNumber() const {
+    return mProducer->getNextFrameNumber();
+}
+
 IBinder* MonitoredProducer::onAsBinder() {
     return IInterface::asBinder(mProducer).get();
 }