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

services/media/framework/parts/null_sink.cc

Index: services/media/framework/parts/null_sink.cc
diff --git a/services/media/framework/parts/null_sink.cc b/services/media/framework/parts/null_sink.cc
index 9c9b29ce54b6f501896143c0b5f923879f122cc8..eb693a847c81e52d6c5885f7bf1566684ea6d38a 100644
--- a/services/media/framework/parts/null_sink.cc
+++ b/services/media/framework/parts/null_sink.cc
@@ -11,15 +11,11 @@ NullSink::NullSink() {}
 
 NullSink::~NullSink() {}
 
-bool NullSink::must_allocate() const {
-  return false;
-}
-
-Allocator* NullSink::allocator() {
+PayloadAllocator* NullSink::allocator() {
   return nullptr;
 }
 
-void NullSink::SetDemandCallback(DemandCallback demand_callback) {
+void NullSink::SetDemandCallback(const DemandCallback& demand_callback) {
   demand_callback_ = demand_callback;
 }