Allow multiple concurrent Decode() requests in VideoDecoder interface.

media/filters/fake_demuxer_stream.cc

Index: media/filters/fake_demuxer_stream.cc
diff --git a/media/filters/fake_demuxer_stream.cc b/media/filters/fake_demuxer_stream.cc
index 5c5ca50ebd455563d809a0bdbc11029707ae6186..f89de1029bef116b0932785b06c66ca8d67f3feb 100644
--- a/media/filters/fake_demuxer_stream.cc
+++ b/media/filters/fake_demuxer_stream.cc
@@ -111,6 +111,15 @@ void FakeDemuxerStream::SatisfyRead() {
   DoRead();
 }
 
+void FakeDemuxerStream::SatisfyAndHoldRead() {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+  DCHECK_EQ(read_to_hold_, next_read_num_);
+  DCHECK(!read_cb_.is_null());
+
+  ++read_to_hold_;
+  DoRead();
+}
+
 void FakeDemuxerStream::Reset() {
   read_to_hold_ = -1;