Motown: Remove LPCM optimizations, fix prepare, add flush, add ActiveMultistreamSink model/stage

services/media/framework/parts/null_sink.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef SERVICES_MEDIA_FRAMEWORK_PARTS_NULL_SINK_H_
 #define SERVICES_MEDIA_FRAMEWORK_PARTS_NULL_SINK_H_
 
 #include "services/media/framework/models/active_sink.h"
 
 namespace mojo {
 namespace media {
 
-class NullSink;
-
-typedef SharedPtr<NullSink, ActiveSink> NullSinkPtr;
-
 // Sink that throws packets away.
 class NullSink : public ActiveSink {
  public:
-  static NullSinkPtr Create() { return NullSinkPtr(new NullSink()); }
+  static std::shared_ptr<NullSink> Create() {
+      return std::shared_ptr<NullSink>(new NullSink());
+  }
 
   ~NullSink() override;
 
   // ActiveSink implementation.
-  bool must_allocate() const override;
+  PayloadAllocator* allocator() override;
 
-  Allocator* allocator() override;
-
-  void SetDemandCallback(DemandCallback demand_callback) override;
+  void SetDemandCallback(const DemandCallback& demand_callback) override;
 
   void Prime() override;
 
   Demand SupplyPacket(PacketPtr packet) override;
 
  private:
   NullSink();
 
   DemandCallback demand_callback_;
 };
 
 }  // namespace media
 }  // namespace mojo
 
 #endif  // SERVICES_MEDIA_FRAMEWORK_PARTS_NULL_SINK_H_