Add methods for telling V8 how much memory audio/video is using.

media/filters/chunk_demuxer.cc

Index: media/filters/chunk_demuxer.cc
diff --git a/media/filters/chunk_demuxer.cc b/media/filters/chunk_demuxer.cc
index eee779bd6009bf36c1d44ac01a812c8ae85f2632..869edfba3eeb90d76a89da2a709c525c2a9b0361 100644
--- a/media/filters/chunk_demuxer.cc
+++ b/media/filters/chunk_demuxer.cc
@@ -1310,6 +1310,12 @@ TimeDelta ChunkDemuxer::GetStartTime() const {
   return TimeDelta();
 }
 
+int64_t ChunkDemuxer::GetMemoryUsage() const {
+  base::AutoLock auto_lock(lock_);
+  return (audio_ ? audio_->GetBufferedSize() : 0) +
+         (video_ ? video_->GetBufferedSize() : 0);
+}
+
 void ChunkDemuxer::StartWaitingForSeek(TimeDelta seek_time) {
   DVLOG(1) << "StartWaitingForSeek()";
   base::AutoLock auto_lock(lock_);