MSE: Give decode error if MDAT discard peek fails

media/formats/mp4/mp4_stream_parser.cc

Index: media/formats/mp4/mp4_stream_parser.cc
diff --git a/media/formats/mp4/mp4_stream_parser.cc b/media/formats/mp4/mp4_stream_parser.cc
index ceefcfa963a0b5840593f13ae52531fde824f6a2..4d56a8c561c0ae37200ea391b41b0009523719ac 100644
--- a/media/formats/mp4/mp4_stream_parser.cc
+++ b/media/formats/mp4/mp4_stream_parser.cc
@@ -550,9 +550,11 @@ bool MP4StreamParser::SendAndFlushSamples(BufferQueue* audio_buffers,
 bool MP4StreamParser::ReadAndDiscardMDATsUntil(const int64 offset) {
   bool err = false;
   while (mdat_tail_ < offset) {
-    const uint8* buf;
-    int size;
+    const uint8* buf = NULL;
+    int size = 0;
     queue_.PeekAt(mdat_tail_, &buf, &size);
+    if (size <= 0)
+      return false;
 
     FourCC type;
     int box_sz;