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

services/media/framework/stages/util.h

Index: services/media/framework/stages/util.h
diff --git a/services/media/framework/stages/stage.cc b/services/media/framework/stages/util.h
similarity index 55%
copy from services/media/framework/stages/stage.cc
copy to services/media/framework/stages/util.h
index 44e925f3dd84bf7a9ba7bf3debab80d0cc26ca45..d04b2dfebc7d5a2d66f2c9d98b059f8b1c895c92 100644
--- a/services/media/framework/stages/stage.cc
+++ b/services/media/framework/stages/util.h
@@ -2,19 +2,19 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "base/logging.h"
+#ifndef SERVICES_MEDIA_FRAMEWORK_STAGES_UTIL_H_
+#define SERVICES_MEDIA_FRAMEWORK_STAGES_UTIL_H_
+
+#include <vector>
+
 #include "services/media/framework/stages/stage.h"
 
 namespace mojo {
 namespace media {
 
-Stage::Stage() : in_supply_backlog_(false), in_demand_backlog_(false) {}
-
-Stage::~Stage() {}
-
-void Stage::UnprepareInput(size_t index) {}
-
-void Stage::UnprepareOutput(size_t index, const UpstreamCallback& callback) {}
+bool HasPositiveDemand(const std::vector<Output>& outputs);
 
 }  // namespace media
 }  // namespace mojo
+
+#endif  // SERVICES_MEDIA_FRAMEWORK_STAGES_UTIL_H_