Accommodate the move of AudioPlaybackRate to system/audio.h

AudioPlaybackRate is now defined in system/audio.h
as 'struct audio_playback_rate_t' (in global namespace).
Similar for the related enums.

To accommodate the existing code, introduce AudioPlaybackRate
as a typedef in the 'android' namespace.

Update code that was forward declaring AudioPlaybackRate
as it's not a struct anymore.

Bug: 133526565
Test: m
Change-Id: Iba20f1de1e8779cd78ac4573f2082416f2b428e2
diff --git a/media/libmediaplayerservice/MediaPlayerService.h b/media/libmediaplayerservice/MediaPlayerService.h
index 2562b8f..6431ca1 100644
--- a/media/libmediaplayerservice/MediaPlayerService.h
+++ b/media/libmediaplayerservice/MediaPlayerService.h
@@ -26,6 +26,7 @@
 #include <utils/String8.h>
 #include <utils/Vector.h>
 
+#include <media/AudioResamplerPublic.h>
 #include <media/AudioSystem.h>
 #include <media/MediaPlayerInterface.h>
 #include <media/Metadata.h>
@@ -36,7 +37,6 @@
 
 namespace android {
 
-struct AudioPlaybackRate;
 class AudioTrack;
 struct AVSyncSettings;
 class DeathNotifier;