capture frame rate for player records

media.metrics gets the frame rate of playback within the nuplayer
records.

Bug: 119817586
Test: logcat
diff --git a/media/libmediaplayerservice/nuplayer/NuPlayerDecoder.cpp b/media/libmediaplayerservice/nuplayer/NuPlayerDecoder.cpp
index 050e4fb..a2ec699 100644
--- a/media/libmediaplayerservice/nuplayer/NuPlayerDecoder.cpp
+++ b/media/libmediaplayerservice/nuplayer/NuPlayerDecoder.cpp
@@ -110,6 +110,7 @@
     mStats->setInt64("frames-total", mNumFramesTotal);
     mStats->setInt64("frames-dropped-input", mNumInputFramesDropped);
     mStats->setInt64("frames-dropped-output", mNumOutputFramesDropped);
+    mStats->setFloat("frame-rate-total", mFrameRateTotal);
     return mStats;
 }