Add MEDIA_STARTED/PAUSED/STOPPED events to media players

This is needed for the MediaTimeProvider java interface, so it does not
continually poll for current media time.

Note: NuPlayer and AwesomePlayer do not correctly handle stop (pause
instead), so for those we will signal PAUSED.

Signed-off-by: Lajos Molnar <lajos@google.com>
Change-Id: I3c61e1bda475f131323f475c18a42e3ec66c9ae1
Bug: 10326117
diff --git a/include/media/mediaplayer.h b/include/media/mediaplayer.h
index 14381c7..1afd7f7 100644
--- a/include/media/mediaplayer.h
+++ b/include/media/mediaplayer.h
@@ -42,6 +42,9 @@
     MEDIA_BUFFERING_UPDATE  = 3,
     MEDIA_SEEK_COMPLETE     = 4,
     MEDIA_SET_VIDEO_SIZE    = 5,
+    MEDIA_STARTED           = 6,
+    MEDIA_PAUSED            = 7,
+    MEDIA_STOPPED           = 8,
     MEDIA_TIMED_TEXT        = 99,
     MEDIA_ERROR             = 100,
     MEDIA_INFO              = 200,