aaudio: implement IPlayer for MMAP playback streams

Make AudioStreamInternal derive from PlayerBase to
provide playback and volume control via IPlayer interface.

Bug: 62027849
Test: verify aaudio playback in MMAP mode and registration of aaudio
players in AudioService when active

Change-Id: Ia0878d46637c0a954d8a6259868a2d3bccf19119
diff --git a/media/libaudioclient/include/media/PlayerBase.h b/media/libaudioclient/include/media/PlayerBase.h
index fe1db7b..e63090b 100644
--- a/media/libaudioclient/include/media/PlayerBase.h
+++ b/media/libaudioclient/include/media/PlayerBase.h
@@ -48,6 +48,8 @@
 
 
             status_t startWithStatus();
+            status_t pauseWithStatus();
+            status_t stopWithStatus();
 
             //FIXME temporary method while some player state is outside of this class
             void reportEvent(player_state_t event);