Add playback rate to AudioTrack

Bug: 19196501
Change-Id: I6411e1d3ce652b711a71a6d9df020cb5f60d4714
diff --git a/media/libmedia/AudioTrackShared.cpp b/media/libmedia/AudioTrackShared.cpp
index 6d5f1af..ba67b40 100644
--- a/media/libmedia/AudioTrackShared.cpp
+++ b/media/libmedia/AudioTrackShared.cpp
@@ -793,6 +793,16 @@
     (void) android_atomic_or(CBLK_UNDERRUN, &cblk->mFlags);
 }
 
+void AudioTrackServerProxy::getPlaybackRate(float *speed, float *pitch)
+{   // do not call from multiple threads without holding lock
+    AudioTrackPlaybackRate playbackRate;
+    if (mPlaybackRateObserver.poll(playbackRate)) {
+        mPlaybackRate = playbackRate;
+    }
+    *speed = mPlaybackRate.mSpeed;
+    *pitch = mPlaybackRate.mPitch;
+}
+
 // ---------------------------------------------------------------------------
 
 StaticAudioTrackServerProxy::StaticAudioTrackServerProxy(audio_track_cblk_t* cblk, void *buffers,