MediaCodec: add background mode

Bug: 183751395
Test: manual
Change-Id: If60634c62d44bb828ba309ce376daeddd5d6332f
diff --git a/media/codec2/sfplugin/InputSurfaceWrapper.h b/media/codec2/sfplugin/InputSurfaceWrapper.h
index 50d600c..44ba78a 100644
--- a/media/codec2/sfplugin/InputSurfaceWrapper.h
+++ b/media/codec2/sfplugin/InputSurfaceWrapper.h
@@ -79,6 +79,7 @@
         float mFixedAdjustedFps = 0.0; // fixed fps via PTS manipulation
         float mMinAdjustedFps = 0.0; // minimum fps via PTS manipulation
         uint64_t mUsage = 0; // consumer usage
+        int mPriority = INT_MAX; // priority of queue thread (if any); INT_MAX for no-op
     };
 
     /**