NuPlayer: update timestamp handling

Use getTimestamp WOULD_BLOCK error return code to clean up
initial playback/start timestamp handling.

Account for pause time and seeks.
Only send notification from driver when the media time changes.

Bug: 14659809
Bug: 17428188
Change-Id: I051bb5e2dd4fd5990474f8fb635615ad8d18eb2c
diff --git a/media/libmediaplayerservice/nuplayer/NuPlayerRenderer.h b/media/libmediaplayerservice/nuplayer/NuPlayerRenderer.h
index 2b32c48..97fdae7 100644
--- a/media/libmediaplayerservice/nuplayer/NuPlayerRenderer.h
+++ b/media/libmediaplayerservice/nuplayer/NuPlayerRenderer.h
@@ -106,7 +106,7 @@
     int32_t mAudioQueueGeneration;
     int32_t mVideoQueueGeneration;
 
-    int64_t mFirstAudioTimeUs;
+    int64_t mFirstAnchorTimeMediaUs;
     int64_t mAnchorTimeMediaUs;
     int64_t mAnchorTimeRealUs;