update offloaded audio track sampling rate

AudioPlayer must read the sampling rate from offloaded audio sinks
whenever a new time position is computed as the decoder can update
the sampling rate on the fly.

Change-Id: I997e5248cfd4017aeceb4e11689324ded2a5bc88
diff --git a/media/libmediaplayerservice/MediaPlayerService.h b/media/libmediaplayerservice/MediaPlayerService.h
index a486cb5..9c084e1 100644
--- a/media/libmediaplayerservice/MediaPlayerService.h
+++ b/media/libmediaplayerservice/MediaPlayerService.h
@@ -86,6 +86,7 @@
         virtual status_t        getPosition(uint32_t *position) const;
         virtual status_t        getFramesWritten(uint32_t *frameswritten) const;
         virtual int             getSessionId() const;
+        virtual uint32_t        getSampleRate() const;
 
         virtual status_t        open(
                 uint32_t sampleRate, int channelCount, audio_channel_mask_t channelMask,
@@ -195,6 +196,7 @@
         virtual status_t        getPosition(uint32_t *position) const;
         virtual status_t        getFramesWritten(uint32_t *frameswritten) const;
         virtual int             getSessionId() const;
+        virtual uint32_t        getSampleRate() const;
 
         virtual status_t        open(
                 uint32_t sampleRate, int channelCount, audio_channel_mask_t channelMask,