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

services/media/framework/stages/multistream_source_stage.cc

Index: services/media/framework/stages/multistream_source_stage.cc
diff --git a/services/media/framework/stages/multistream_source_stage.cc b/services/media/framework/stages/multistream_source_stage.cc
new file mode 100644
index 0000000000000000000000000000000000000000..3d64ba05a128a5c9953f720f6a19bbce39978c53
--- /dev/null
+++ b/services/media/framework/stages/multistream_source_stage.cc
@@ -0,0 +1,124 @@
+// 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/multistream_source_stage.h"
+
+namespace mojo {
+namespace media {
+
+MultistreamSourceStage::MultistreamSourceStage(
+    std::shared_ptr<MultistreamSource> source) :
+    source_(source),
+    ended_streams_(0) {
+  DCHECK(source);
+  outputs_.resize(source->stream_count());
+}
+
+MultistreamSourceStage::~MultistreamSourceStage() {}
+
+size_t MultistreamSourceStage::input_count() const {
+  return 0;
+};
+
+Input& MultistreamSourceStage::input(size_t index) {
+  CHECK(false) << "input requested from source";
+  return *(static_cast<Input*>(nullptr));
+}
+
+size_t MultistreamSourceStage::output_count() const {
+  return outputs_.size();
+}
+
+Output& MultistreamSourceStage::output(size_t index) {
+  DCHECK(index < outputs_.size());
+  return outputs_[index];
+}
+
+PayloadAllocator* MultistreamSourceStage::PrepareInput(size_t index) {
+  CHECK(false) << "PrepareInput called on source";
+  return nullptr;
+}
+
+void MultistreamSourceStage::PrepareOutput(
+    size_t index,
+    PayloadAllocator* allocator,
+    const UpstreamCallback& callback) {
+  DCHECK(index < outputs_.size());
+
+  if (allocator != nullptr) {
+    // Currently, we don't support a source that uses provided allocators. If
+    // we're provided an allocator, the output must have it so supplied packets
+    // can be copied.
+    outputs_[index].SetCopyAllocator(allocator);
+  }
+}
+
+void MultistreamSourceStage::UnprepareOutput(
+    size_t index,
+    const UpstreamCallback& callback) {
+  DCHECK(index < outputs_.size());
+  outputs_[index].SetCopyAllocator(nullptr);
+}
+
+void MultistreamSourceStage::Update(Engine* engine) {
+  DCHECK(engine);
+
+  bool has_positive_demand = false;
+  for (Output& output : outputs_) {
+    if (output.demand() == Demand::kPositive) {
+      has_positive_demand = true;
+      break;
+    }
+  }
+
+  while (true) {
+    if (cached_packet_ && has_positive_demand) {
+      DCHECK(cached_packet_output_index_ < outputs_.size());
+      Output& output = outputs_[cached_packet_output_index_];
+
+      if (output.demand() != Demand::kNegative) {
+        // cached_packet_ is intended for an output which will accept packets.
+        output.SupplyPacket(std::move(cached_packet_), engine);
+      }
+    }
+
+    if (cached_packet_) {
+      // There's still a cached packet. We're done for now.
+      return;
+    }
+
+    if (ended_streams_ == outputs_.size()) {
+      // We've seen end-of-stream for all streams. All done.
+      return;
+    }
+
+    // Pull a packet from the source.
+    cached_packet_ = source_->PullPacket(&cached_packet_output_index_);
+    DCHECK(cached_packet_);
+    DCHECK(cached_packet_output_index_ < outputs_.size());
+
+    if (cached_packet_->end_of_stream()) {
+      ended_streams_++;
+    }
+  }
+}
+
+void MultistreamSourceStage::FlushInput(
+    size_t index,
+    const DownstreamCallback& callback) {
+  CHECK(false) << "FlushInput called on source";
+}
+
+void MultistreamSourceStage::FlushOutput(size_t index) {
+  DCHECK(index < outputs_.size());
+  DCHECK(source_);
+  outputs_[index].Flush();
+  source_->Flush();
+  cached_packet_.reset(nullptr);
+  cached_packet_output_index_ = 0;
+  ended_streams_ = 0;
+}
+
+}  // namespace media
+}  // namespace mojo