NuPlayer: Enhance dumpsys statistics

Account for dropped output-frames (rather than input-frames)
in percentage dropped frames.
Print mime and component name for each active track

Change-Id: I3491d336c696d8ed0fd1503b80afe1df47c787c8
diff --git a/media/libmediaplayerservice/nuplayer/NuPlayerDecoderBase.cpp b/media/libmediaplayerservice/nuplayer/NuPlayerDecoderBase.cpp
index 9d509bf..7e76842 100644
--- a/media/libmediaplayerservice/nuplayer/NuPlayerDecoderBase.cpp
+++ b/media/libmediaplayerservice/nuplayer/NuPlayerDecoderBase.cpp
@@ -31,6 +31,7 @@
 NuPlayer::DecoderBase::DecoderBase(const sp<AMessage> &notify)
     :  mNotify(notify),
        mBufferGeneration(0),
+       mStats(new AMessage),
        mRequestInputBuffersPending(false) {
     // Every decoder has its own looper because MediaCodec operations
     // are blocking, but NuPlayer needs asynchronous operations.