NuPlayer: invalid anchor time when render is flushed.

Also rememeber the pause time in NuPlayerDriver.

Bug: 18436336
Change-Id: If09f680a0d0f9137bd55c5f94201eb3aa783278a
diff --git a/media/libmediaplayerservice/nuplayer/NuPlayerRenderer.cpp b/media/libmediaplayerservice/nuplayer/NuPlayerRenderer.cpp
index 73bc829..f27826c 100644
--- a/media/libmediaplayerservice/nuplayer/NuPlayerRenderer.cpp
+++ b/media/libmediaplayerservice/nuplayer/NuPlayerRenderer.cpp
@@ -1029,6 +1029,7 @@
          Mutex::Autolock autoLock(mLock);
          syncQueuesDone_l();
          setPauseStartedTimeRealUs(-1);
+         setAnchorTime(-1, -1);
     }
 
     ALOGV("flushing %s", audio ? "audio" : "video");