NuPlayer: make previous decoders obsolete when reset is done.

Bug: 17428608
Change-Id: I724174d65f8e00bfecb51e6f690ae709ed2cf442
diff --git a/media/libmediaplayerservice/nuplayer/NuPlayer.cpp b/media/libmediaplayerservice/nuplayer/NuPlayer.cpp
index a44de98..59766c8 100644
--- a/media/libmediaplayerservice/nuplayer/NuPlayer.cpp
+++ b/media/libmediaplayerservice/nuplayer/NuPlayer.cpp
@@ -1833,6 +1833,9 @@
     ++mScanSourcesGeneration;
     mScanSourcesPending = false;
 
+    ++mAudioDecoderGeneration;
+    ++mVideoDecoderGeneration;
+
     if (mRendererLooper != NULL) {
         if (mRenderer != NULL) {
             mRendererLooper->unregisterHandler(mRenderer->id());