Stop assuming metadata contains at least one stream

media/blink/webmediaplayer_impl.cc

Index: media/blink/webmediaplayer_impl.cc
diff --git a/media/blink/webmediaplayer_impl.cc b/media/blink/webmediaplayer_impl.cc
index c6188abcc7c279c0a80eecdcf279ee7026432b9f..073decac2b844b411cd38a1bfa37ac8fa523d93d 100644
--- a/media/blink/webmediaplayer_impl.cc
+++ b/media/blink/webmediaplayer_impl.cc
@@ -2303,6 +2303,9 @@ void WebMediaPlayerImpl::ScheduleIdlePauseTimer() {
 }
 
 void WebMediaPlayerImpl::CreateWatchTimeReporter() {
+  if (!HasVideo() && !HasAudio())
+    return;
+
   // Create the watch time reporter and synchronize its initial state.
   watch_time_reporter_.reset(
       new WatchTimeReporter(HasAudio(), HasVideo(), !!chunk_demuxer_,