Motown in-proc streaming framework used to implement media services.

services/media/framework/stages/active_source_stage.cc

Index: services/media/framework/stages/active_source_stage.cc
diff --git a/services/media/framework/stages/active_source_stage.cc b/services/media/framework/stages/active_source_stage.cc
new file mode 100644
index 0000000000000000000000000000000000000000..6dd2fc99595554d238d90f6942e05e704eca6b34
--- /dev/null
+++ b/services/media/framework/stages/active_source_stage.cc
@@ -0,0 +1,69 @@
+// 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.
+
+#include "services/media/framework/stages/active_source_stage.h"
+
+namespace mojo {
+namespace media {
+
+ActiveSourceStage::ActiveSourceStage(ActiveSourcePtr source) : source_(source) {
+  DCHECK(source_);
+
+  supply_function_ = [this](PacketPtr packet) {
+    bool packets_was_empty_ = packets_.empty();
+    packets_.push_back(std::move(packet));
+    if (packets_was_empty_ && update_callback_) {
+      update_callback_(this);
+    }
+  };
+
+  source_->SetSupplyCallback(supply_function_);
+}
+
+ActiveSourceStage::~ActiveSourceStage() {}
+
+uint32_t ActiveSourceStage::input_count() const {
+  return 0;
+};
+
+StageInput& ActiveSourceStage::input(uint32_t index) {
+  NOTREACHED();
+  static StageInput result;
+  return result;
+}
+
+uint32_t ActiveSourceStage::output_count() const {
+  return 1;
+}
+
+StageOutput& ActiveSourceStage::output(uint32_t index) {
+  DCHECK_EQ(index, 0u);
+  return output_;
+}
+
+bool ActiveSourceStage::Prepare(UpdateCallback update_callback) {
+  update_callback_ = update_callback;
+  Allocator* allocator = output_.Prepare(source_->can_accept_allocator());
+  if (allocator) {
+    DCHECK(source_->can_accept_allocator());
+    source_->set_allocator(allocator);
+  }
+  return true;
+}
+
+void ActiveSourceStage::Update(Engine* engine) {
+  DCHECK(engine);
+
+  Demand demand = output_.demand();
+
+  source_->SetDownstreamDemand(demand);
+
+  if (demand != Demand::kNegative && !packets_.empty()) {
+    output_.SupplyPacket(std::move(packets_.front()), engine);
+    packets_.pop_front();
+  }
+}
+
+}  // namespace media
+}  // namespace mojo