Overlay could not set position or rotation immediately after created, it should be triggered by signalEvent().
Originally from: https://partner.source.android.com/g/#change,1074
diff --git a/libs/surfaceflinger/LayerBuffer.cpp b/libs/surfaceflinger/LayerBuffer.cpp
index 38a897d..667571b 100644
--- a/libs/surfaceflinger/LayerBuffer.cpp
+++ b/libs/surfaceflinger/LayerBuffer.cpp
@@ -595,6 +595,7 @@
 
     *overlayRef = new OverlayRef(mOverlayHandle, channel,
             mWidth, mHeight, mFormat, mWidthStride, mHeightStride);
+    mLayer.mFlinger->signalEvent();
 }
 
 LayerBuffer::OverlaySource::~OverlaySource()