HLS: clear ATSParser fully on explicit discontinuity

After a discontinuity stream PIDs might change in a way that we cannot
recover; creating a brand new parser avoids this potential issue.

Bug: 28320768
Change-Id: I387a9cd2371b11c2b1c0b8b81b85999033e22f7f
diff --git a/media/libstagefright/httplive/PlaylistFetcher.cpp b/media/libstagefright/httplive/PlaylistFetcher.cpp
index 0a1ed94..102c83d 100644
--- a/media/libstagefright/httplive/PlaylistFetcher.cpp
+++ b/media/libstagefright/httplive/PlaylistFetcher.cpp
@@ -1180,8 +1180,7 @@
         // Signal a format discontinuity to ATSParser to clear partial data
         // from previous streams. Not doing this causes bitstream corruption.
         if (mTSParser != NULL) {
-            mTSParser->signalDiscontinuity(
-                    ATSParser::DISCONTINUITY_FORMATCHANGE, NULL /* extra */);
+            mTSParser.clear();
         }
 
         queueDiscontinuity(