Motown: Add ActiveMultistreamSource model in preparation for the ffmpeg demux with async I/O

services/media/framework/stages/util.cc

Index: services/media/framework/stages/util.cc
diff --git a/services/media/framework_ffmpeg/ffmpeg_init.h b/services/media/framework/stages/util.cc
similarity index 50%
copy from services/media/framework_ffmpeg/ffmpeg_init.h
copy to services/media/framework/stages/util.cc
index 75aedf17616861eeaefecd0a7cb27af785307710..0b3393a56dfd8e4775ca08fbc6aeb90420ba56ae 100644
--- a/services/media/framework_ffmpeg/ffmpeg_init.h
+++ b/services/media/framework/stages/util.cc
@@ -2,15 +2,20 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef SERVICES_MEDIA_FRAMEWORK_FFMPEG_FFMPEG_INIT_H_
-#define SERVICES_MEDIA_FRAMEWORK_FFMPEG_FFMPEG_INIT_H_
+#include "services/media/framework/stages/util.h"
 
 namespace mojo {
 namespace media {
 
-void InitFfmpeg();
+bool HasPositiveDemand(const std::vector<Output>& outputs) {
+  for (const Output& output : outputs) {
+    if (output.demand() == Demand::kPositive) {
+      return true;
+    }
+  }
+
+  return false;
+}
 
 }  // namespace media
 }  // namespace mojo
-
-#endif  // SERVICES_MEDIA_FRAMEWORK_FFMPEG_FFMPEG_INIT_H_