nuplayer: Fix incorrect audio resume time during seek

GenericSource uses the timestamp of last video buffer
read in readBuffer() to seek audio, due to which audio
starts at a later position leading to frame drops.

Add change to use the first video sample timestamp
to seek audio

Bug: 22770523

CRs-Fixed: 780094
Author: Xavier Varricatt <xvarrica@codeaurora.org>
Change-Id: I5f2061e67994a3a0330b527bd3164ee04ed04005
diff --git a/media/libmediaplayerservice/nuplayer/GenericSource.cpp b/media/libmediaplayerservice/nuplayer/GenericSource.cpp
index 7dc9be7..27a2934 100644
--- a/media/libmediaplayerservice/nuplayer/GenericSource.cpp
+++ b/media/libmediaplayerservice/nuplayer/GenericSource.cpp
@@ -1521,7 +1521,8 @@
             queueDiscontinuityIfNeeded(seeking, formatChange, trackType, track);
 
             sp<ABuffer> buffer = mediaBufferToABuffer(
-                    mbuf, trackType, seekTimeUs, actualTimeUs);
+                    mbuf, trackType, seekTimeUs,
+                    numBuffers == 0 ? actualTimeUs : NULL);
             track->mPackets->queueAccessUnit(buffer);
             formatChange = false;
             seeking = false;