AudioTrack: Fix extended timestamp offset

The extended timestamp server and kernel location positions
need the proper client side delta offset for native AudioTrack API calls.
The client location position is unaffected along with the legacy timestamp.

Test: test_timestamp, Photos, kill audioserver
Bug: 65386236
Change-Id: Idd71b6a31e0e86a323d0e5e343a2836e34c08673

media/libaudioclient/AudioTrack.cpp

@@ -615,7 +615,8 @@ status_t AudioTrack::start()
                             + mStartEts.mPosition[ExtendedTimestamp::LOCATION_SERVER]),
                     (long long)mStartEts.mFlushed,
                     (long long)mFramesWritten);
-            mFramesWrittenServerOffset = -mStartEts.mPosition[ExtendedTimestamp::LOCATION_SERVER];
+            // mStartEts is already adjusted by mFramesWrittenServerOffset, so we delta adjust.
+            mFramesWrittenServerOffset -= mStartEts.mPosition[ExtendedTimestamp::LOCATION_SERVER];
         }
         mFramesWritten = 0;
         mProxy->clearTimestamp(); // need new server push for valid timestamp