Media Remoting: Data/Control plumbing between renderer and Media Router.

chrome/browser/media/cast_remoting_sender_unittest.cc

Index: chrome/browser/media/cast_remoting_sender_unittest.cc
diff --git a/chrome/browser/media/cast_remoting_sender_unittest.cc b/chrome/browser/media/cast_remoting_sender_unittest.cc
index dd86bd6a16f5043ebdff3a62671ac6a622ec1316..80501710a8d31faa472168d34558b46360363033 100644
--- a/chrome/browser/media/cast_remoting_sender_unittest.cc
+++ b/chrome/browser/media/cast_remoting_sender_unittest.cc
@@ -5,91 +5,99 @@
 #include "chrome/browser/media/cast_remoting_sender.h"
 
 #include "base/bind.h"
+#include "base/bind_helpers.h"
+#include "base/callback_helpers.h"
+#include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
-#include "base/test/simple_test_tick_clock.h"
-#include "media/base/fake_single_thread_task_runner.h"
+#include "base/run_loop.h"
+#include "base/time/default_tick_clock.h"
+#include "content/public/test/test_browser_thread_bundle.h"
 #include "media/cast/cast_environment.h"
 #include "media/cast/constants.h"
-#include "media/cast/logging/simple_event_subscriber.h"
-#include "media/cast/net/cast_transport_config.h"
-#include "media/cast/net/cast_transport_impl.h"
-#include "media/cast/net/pacing/paced_sender.h"
+#include "media/cast/net/cast_transport.h"
 #include "media/cast/test/utility/default_config.h"
-#include "testing/gmock/include/gmock/gmock.h"
+#include "media/mojo/interfaces/remoting.mojom.h"
+#include "mojo/public/cpp/system/data_pipe.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace cast {
 
 namespace {
 
-// Number of bytes in each faked frame.
-constexpr int kFrameSize = 5000;
+// Data pipe capacity is 1KB.
+constexpr int kDataPipeCapacity = 1024;
 
-class TestPacketSender : public media::cast::PacketTransport {
+// Implements the CastTransport interface to capture output from the
+// CastRemotingSender.
+class FakeTransport : public media::cast::CastTransport {
  public:
-  TestPacketSender()
-      : number_of_rtp_packets_(0), number_of_rtcp_packets_(0), paused_(false) {}
-
-  // A singular packet implies a RTCP packet.
-  bool SendPacket(media::cast::PacketRef packet,
-                  const base::Closure& cb) final {
-    if (paused_) {
-      stored_packet_ = packet;
-      callback_ = cb;
-      return false;
-    }
-    if (media::cast::IsRtcpPacket(&packet->data[0], packet->data.size())) {
-      ++number_of_rtcp_packets_;
-    } else {
-      ++number_of_rtp_packets_;
-    }
-    return true;
-  }
+  FakeTransport() {}
+  ~FakeTransport() final {}
 
-  int64_t GetBytesSent() final { return 0; }
+  void TakeSentFrames(std::vector<media::cast::EncodedFrame>* frames) {
+    frames->swap(sent_frames_);
+    sent_frames_.clear();
+  }
 
-  void StartReceiving(const media::cast::PacketReceiverCallbackWithStatus&
-                          packet_receiver) final {}
+  void TakeCanceledFrameIds(std::vector<media::cast::FrameId>* frame_ids) {
+    frame_ids->swap(canceled_frame_ids_);
+    canceled_frame_ids_.clear();
+  }
 
-  void StopReceiving() final {}
+  media::cast::FrameId WaitForKickstart() {
+    base::RunLoop run_loop;
+    kickstarted_callback_ = run_loop.QuitClosure();
+    run_loop.Run();
+    return kickstarted_frame_id_;
+  }
 
-  int number_of_rtp_packets() const { return number_of_rtp_packets_; }
+ protected:
+  void InsertFrame(uint32_t ssrc,
+                   const media::cast::EncodedFrame& frame) final {
+    sent_frames_.push_back(frame);
+  }
 
-  int number_of_rtcp_packets() const { return number_of_rtcp_packets_; }
+  void CancelSendingFrames(
+      uint32_t ssrc, const std::vector<media::cast::FrameId>& frame_ids) final {
+    for (media::cast::FrameId frame_id : frame_ids)
+      canceled_frame_ids_.push_back(frame_id);
+  }
 
-  void SetPause(bool paused) {
-    paused_ = paused;
-    if (!paused && stored_packet_.get()) {
-      SendPacket(stored_packet_, callback_);
-      callback_.Run();
-    }
+  void ResendFrameForKickstart(uint32_t ssrc,
+                               media::cast::FrameId frame_id) final {
+    kickstarted_frame_id_ = frame_id;
+    if (!kickstarted_callback_.is_null())
+      base::ResetAndReturn(&kickstarted_callback_).Run();
   }
 
+  // The rest of the interface is not used for these tests.
+  void SendSenderReport(
+      uint32_t ssrc, base::TimeTicks current_time,
+      media::cast::RtpTimeTicks current_time_as_rtp_timestamp) final {}
+  void AddValidRtpReceiver(uint32_t rtp_sender_ssrc,
+                           uint32_t rtp_receiver_ssrc) final {}
+  void InitializeRtpReceiverRtcpBuilder(
+      uint32_t rtp_receiver_ssrc,
+      const media::cast::RtcpTimeData& time_data) final {}
+  void AddCastFeedback(const media::cast::RtcpCastMessage& cast_message,
+                       base::TimeDelta target_delay) final {}
+  void AddPli(const media::cast::RtcpPliMessage& pli_message) final {}
+  void AddRtcpEvents(
+      const media::cast::ReceiverRtcpEventSubscriber::RtcpEvents& e) final {}
+  void AddRtpReceiverReport(const media::cast::RtcpReportBlock& b) final {}
+  void SendRtcpFromRtpReceiver() final {}
+  void SetOptions(const base::DictionaryValue& options) final {}
+
  private:
-  int number_of_rtp_packets_;
-  int number_of_rtcp_packets_;
-  bool paused_;
-  base::Closure callback_;
-  media::cast::PacketRef stored_packet_;
+  const scoped_refptr<media::cast::CastEnvironment> cast_environment_;
+  std::vector<media::cast::EncodedFrame> sent_frames_;
+  std::vector<media::cast::FrameId> canceled_frame_ids_;
 
-  DISALLOW_COPY_AND_ASSIGN(TestPacketSender);
-};
+  base::Closure kickstarted_callback_;
+  media::cast::FrameId kickstarted_frame_id_;
 
-class DummyClient : public media::cast::CastTransport::Client {
- public:
-  DummyClient() {}
-
-  void OnStatusChanged(media::cast::CastTransportStatus status) final {
-    EXPECT_EQ(media::cast::TRANSPORT_STREAM_INITIALIZED, status);
-  };
-  void OnLoggingEventsReceived(
-      std::unique_ptr<std::vector<media::cast::FrameEvent>> frame_events,
-      std::unique_ptr<std::vector<media::cast::PacketEvent>> packet_events)
-      final {}
-  void ProcessRtpPacket(std::unique_ptr<media::cast::Packet> packet) final {}
-
-  DISALLOW_COPY_AND_ASSIGN(DummyClient);
+  DISALLOW_COPY_AND_ASSIGN(FakeTransport);
 };
 
 }  // namespace
@@ -97,107 +105,491 @@ class DummyClient : public media::cast::CastTransport::Client {
 class CastRemotingSenderTest : public ::testing::Test {
  protected:
   CastRemotingSenderTest()
-      : testing_clock_(new base::SimpleTestTickClock()),
-        task_runner_(new media::FakeSingleThreadTaskRunner(testing_clock_)),
-        cast_environment_(
-            new media::cast::CastEnvironment(base::WrapUnique(testing_clock_),
-                                             task_runner_,
-                                             task_runner_,
-                                             task_runner_)) {
-    testing_clock_->Advance(base::TimeTicks::Now() - base::TimeTicks());
-    transport_ = new TestPacketSender();
-    transport_sender_.reset(new media::cast::CastTransportImpl(
-        testing_clock_, base::TimeDelta(), base::MakeUnique<DummyClient>(),
-        base::WrapUnique(transport_), task_runner_));
+      : thread_bundle_(content::TestBrowserThreadBundle::IO_MAINLOOP),
+        cast_environment_(new media::cast::CastEnvironment(
+            base::WrapUnique(new base::DefaultTickClock()),
+            base::ThreadTaskRunnerHandle::Get(), nullptr, nullptr)),
+        expecting_error_callback_run_(false) {
+
     media::cast::FrameSenderConfig video_config =
         media::cast::GetDefaultVideoSenderConfig();
     video_config.rtp_payload_type = media::cast::RtpPayloadType::REMOTE_VIDEO;
-    media::cast::CastTransportRtpConfig transport_config;
-    transport_config.ssrc = video_config.sender_ssrc;
-    transport_config.rtp_stream_id = 5;
-    transport_config.feedback_ssrc = video_config.receiver_ssrc;
-    transport_config.rtp_payload_type = video_config.rtp_payload_type;
-    transport_config.aes_key = video_config.aes_key;
-    transport_config.aes_iv_mask = video_config.aes_iv_mask;
+    transport_config_.ssrc = video_config.sender_ssrc;
+    transport_config_.rtp_stream_id = 5;
+    transport_config_.feedback_ssrc = video_config.receiver_ssrc;
+    transport_config_.rtp_payload_type = video_config.rtp_payload_type;
+    transport_config_.aes_key = video_config.aes_key;
+    transport_config_.aes_iv_mask = video_config.aes_iv_mask;
     remoting_sender_.reset(new CastRemotingSender(
-        cast_environment_, transport_sender_.get(), transport_config));
-    task_runner_->RunTasks();
+        cast_environment_, &transport_, transport_config_));
+    // Give CastRemotingSender a small RTT measurement to prevent kickstart
+    // testing from taking too long.
+    remoting_sender_->OnReceivedRtt(base::TimeDelta::FromMilliseconds(1));
+
+    const MojoCreateDataPipeOptions data_pipe_options{
+        sizeof(MojoCreateDataPipeOptions),
+        MOJO_CREATE_DATA_PIPE_OPTIONS_FLAG_NONE, 1, kDataPipeCapacity };
+    mojo::ScopedDataPipeConsumerHandle consumer_end;
+    CHECK_EQ(MOJO_RESULT_OK,
+             mojo::CreateDataPipe(&data_pipe_options, &producer_end_,
+                                  &consumer_end));
+
+    CastRemotingSender::FindAndBind(
+        transport_config_.rtp_stream_id, std::move(consumer_end),
+        GetProxy(&sender_),
+        base::Bind(&CastRemotingSenderTest::OnError, base::Unretained(this)));
+
+    RunPendingTasks();
   }
 
   ~CastRemotingSenderTest() override {}
 
   void TearDown() final {
     remoting_sender_.reset();
-    task_runner_->RunTasks();
+    // Allow any pending tasks to run before destruction.
+    RunPendingTasks();
   }
 
-  void InsertFrame() {
-    remoting_sender_->next_frame_data_.resize(kFrameSize);
-    remoting_sender_->SendFrame();
+  // Allow pending tasks, such as Mojo method calls, to execute.
+  static void RunPendingTasks() {
+    base::RunLoop().RunUntilIdle();
   }
 
-  void OnReceivedCastMessage(
-      const media::cast::RtcpCastMessage& cast_feedback) {
-    remoting_sender_->OnReceivedCastMessage(cast_feedback);
+ protected:
+  media::cast::FrameId latest_acked_frame_id() const {
+    return remoting_sender_->latest_acked_frame_id_;
   }
 
   int NumberOfFramesInFlight() {
     return remoting_sender_->NumberOfFramesInFlight();
   }
 
-  void CancelFramesInFlight() { remoting_sender_->CancelFramesInFlight(); }
+  size_t GetSizeOfNextFrameData() {
+    return remoting_sender_->next_frame_data_.size();
+  }
+
+  bool IsFlowControlInRestartingState() const {
+    return remoting_sender_->flow_control_state_ ==
+        CastRemotingSender::RESTARTING;
+  }
+  bool IsFlowControlInConsumingState() const {
+    return remoting_sender_->flow_control_state_ ==
+        CastRemotingSender::CONSUMING;
+  }
+  bool IsFlowControlInPausedState() const {
+    return remoting_sender_->flow_control_state_ ==
+        CastRemotingSender::CONSUME_PAUSED;
+  }
+
+  bool ProduceDataChunk(size_t offset, size_t size) WARN_UNUSED_RESULT {
+    std::vector<uint8_t> fake_chunk(size);
+    for (size_t i = 0; i < size; ++i)
+      fake_chunk[i] = static_cast<uint8_t>(offset + i);
+    uint32_t num_bytes = fake_chunk.size();
+    return mojo::WriteDataRaw(
+        producer_end_.get(), fake_chunk.data(), &num_bytes,
+        MOJO_WRITE_DATA_FLAG_ALL_OR_NONE) == MOJO_RESULT_OK;
+  }
+
+  void PostMojoCallTask_ConsumeDataChunk(size_t offset, size_t size,
+                                         size_t total_payload_size) {
+    sender_->ConsumeDataChunk(offset, size, total_payload_size);
+  }
+
+  void PostMojoCallTask_SendFrame() {
+    sender_->SendFrame();
+  }
+
+  void PostMojoCallTask_CancelInFlightData() { sender_->CancelInFlightData(); }
+
+  void TakeSentFrames(std::vector<media::cast::EncodedFrame>* frames) {
+    transport_.TakeSentFrames(frames);
+  }
+
+  bool ExpectOneFrameWasSent(size_t expected_payload_size) {
+    std::vector<media::cast::EncodedFrame> frames;
+    transport_.TakeSentFrames(&frames);
+    EXPECT_EQ(1u, frames.size());
+    if (frames.empty())
+      return false;
+    return ExpectCorrectFrameData(expected_payload_size, frames.front());
+  }
+
+  void AckUpToAndIncluding(media::cast::FrameId frame_id) {
+    media::cast::RtcpCastMessage cast_feedback(transport_config_.feedback_ssrc);
+    cast_feedback.ack_frame_id = frame_id;
+    remoting_sender_->OnReceivedCastMessage(cast_feedback);
+  }
+
+  void AckOldestInFlightFrames(int count) {
+    AckUpToAndIncluding(latest_acked_frame_id() + count);
+  }
+
+  // Blocks the caller indefinitely, until a kickstart frame is sent, and then
+  // returns the FrameId of the kickstarted-frame.
+  media::cast::FrameId WaitForKickstart() {
+    return transport_.WaitForKickstart();
+  }
+
+  bool ExpectNoFramesCanceled() {
+    std::vector<media::cast::FrameId> frame_ids;
+    transport_.TakeCanceledFrameIds(&frame_ids);
+    return frame_ids.empty();
+  }
+
+  bool ExpectFramesCanceled(media::cast::FrameId first_frame_id,
+                            media::cast::FrameId last_frame_id) {
+    std::vector<media::cast::FrameId> frame_ids;
+    transport_.TakeCanceledFrameIds(&frame_ids);
+    auto begin = frame_ids.begin();
+    auto end = frame_ids.end();
+    for (auto fid = first_frame_id; fid <= last_frame_id; ++fid) {
+      auto new_end = std::remove(begin, end, fid);
+      if (new_end == end)
+        return false;
+      end = new_end;
+    }
+    return begin == end;
+  }
 
-  base::SimpleTestTickClock* const testing_clock_;  // Owned by CastEnvironment.
-  const scoped_refptr<media::FakeSingleThreadTaskRunner> task_runner_;
+  static bool ExpectCorrectFrameData(size_t expected_payload_size,
+                                     const media::cast::EncodedFrame& frame) {
+    if (expected_payload_size != frame.data.size()) {
+      ADD_FAILURE() << "Expected frame data size != frame.data.size(): "
+                    << expected_payload_size << " vs " << frame.data.size();
+      return false;
+    }
+    for (size_t i = 0; i < expected_payload_size; ++i) {
+      if (static_cast<uint8_t>(frame.data[i]) != static_cast<uint8_t>(i)) {
+        ADD_FAILURE() << "Frame data byte mismatch at offset " << i;
+        return false;
+      }
+    }
+    return true;
+  }
+
+ private:
+  void OnError() {
+    CHECK(expecting_error_callback_run_);
+  }
+
+  content::TestBrowserThreadBundle thread_bundle_;
   const scoped_refptr<media::cast::CastEnvironment> cast_environment_;
-  TestPacketSender* transport_;  // Owned by CastTransport.
-  std::unique_ptr<media::cast::CastTransportImpl> transport_sender_;
+  media::cast::CastTransportRtpConfig transport_config_;
+  FakeTransport transport_;
   std::unique_ptr<CastRemotingSender> remoting_sender_;
+  media::mojom::RemotingDataStreamSenderPtr sender_;
+  mojo::ScopedDataPipeProducerHandle producer_end_;
+  bool expecting_error_callback_run_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(CastRemotingSenderTest);
 };
 
-TEST_F(CastRemotingSenderTest, SendAndAckEncodedFrame) {
-  // Send a fake video frame that will be decomposed into 4 packets.
-  InsertFrame();
-  task_runner_->RunTasks();
-  EXPECT_EQ(4, transport_->number_of_rtp_packets());
-  EXPECT_EQ(1, NumberOfFramesInFlight());
-
-  // Ack the frame.
-  media::cast::RtcpCastMessage cast_feedback(11);
-  cast_feedback.ack_frame_id = media::cast::FrameId::first();
-  OnReceivedCastMessage(cast_feedback);
-  EXPECT_EQ(0, NumberOfFramesInFlight());
+TEST_F(CastRemotingSenderTest, SendsFramesViaMojoInterface) {
+  // One 256-byte chunk pushed through the data pipe to make one frame.
+  ASSERT_TRUE(ProduceDataChunk(0, 256));
+  PostMojoCallTask_ConsumeDataChunk(0, 256, 256);
+  PostMojoCallTask_SendFrame();
+  RunPendingTasks();
+  EXPECT_TRUE(ExpectOneFrameWasSent(256));
+  AckOldestInFlightFrames(1);
+  EXPECT_EQ(media::cast::FrameId::first(), latest_acked_frame_id());
+
+  // Four 256-byte chunks pushed through the data pipe to make one frame.
+  for (int i = 0; i < 4; ++i) {
+    ASSERT_TRUE(ProduceDataChunk(i * 256, 256));
+    PostMojoCallTask_ConsumeDataChunk(i * 256, 256, 1024);
+  }
+  PostMojoCallTask_SendFrame();
+  RunPendingTasks();
+  EXPECT_TRUE(ExpectOneFrameWasSent(1024));
+  AckOldestInFlightFrames(1);
+  EXPECT_EQ(media::cast::FrameId::first() + 1, latest_acked_frame_id());
+
+  // 10 differently-sized chunks pushed through the data pipe to make one frame
+  // that is larger than the data pipe's total capacity.
+  size_t offset = 0;
+  for (int i = 0; i < 10; ++i) {
+    const size_t chunk_size = 500 + i * 37;
+    ASSERT_TRUE(ProduceDataChunk(offset, chunk_size));
+    PostMojoCallTask_ConsumeDataChunk(offset, chunk_size, 6665);
+    RunPendingTasks();
+    offset += chunk_size;
+  }
+  PostMojoCallTask_SendFrame();
+  RunPendingTasks();
+  EXPECT_TRUE(ExpectOneFrameWasSent(6665));
+  AckOldestInFlightFrames(1);
+  EXPECT_EQ(media::cast::FrameId::first() + 2, latest_acked_frame_id());
+}
 
+TEST_F(CastRemotingSenderTest, SendsMultipleFramesWithDelayedAcks) {
   // Send 4 frames.
-  for (int i = 0; i < 4; ++i)
-    InsertFrame();
+  for (int i = 0; i < 4; ++i) {
+    ASSERT_TRUE(ProduceDataChunk(0, 16));
+    PostMojoCallTask_ConsumeDataChunk(0, 16, 16);
+    PostMojoCallTask_SendFrame();
+  }
+  RunPendingTasks();
   EXPECT_EQ(4, NumberOfFramesInFlight());
+  EXPECT_TRUE(ExpectNoFramesCanceled());
+
   // Ack one frame.
-  cast_feedback.ack_frame_id = media::cast::FrameId::first() + 1;
-  OnReceivedCastMessage(cast_feedback);
+  AckOldestInFlightFrames(1);
   EXPECT_EQ(3, NumberOfFramesInFlight());
+  EXPECT_TRUE(ExpectFramesCanceled(media::cast::FrameId::first(),
+                                   media::cast::FrameId::first()));
+
   // Ack all.
-  cast_feedback.received_later_frames.clear();
-  cast_feedback.ack_frame_id = media::cast::FrameId::first() + 4;
-  OnReceivedCastMessage(cast_feedback);
+  AckOldestInFlightFrames(3);
   EXPECT_EQ(0, NumberOfFramesInFlight());
+  EXPECT_TRUE(ExpectFramesCanceled(media::cast::FrameId::first() + 1,
+                                   media::cast::FrameId::first() + 3));
+}
+
+TEST_F(CastRemotingSenderTest, KickstartsIfAckNotTimely) {
+  // Send first frame and don't Ack it. Expect the first frame to be
+  // kickstarted.
+  ASSERT_TRUE(ProduceDataChunk(0, 16));
+  PostMojoCallTask_ConsumeDataChunk(0, 16, 16);
+  PostMojoCallTask_SendFrame();
+  EXPECT_EQ(media::cast::FrameId::first(), WaitForKickstart());
+  EXPECT_EQ(1, NumberOfFramesInFlight());
+
+  // Send 3 more frames and don't Ack them either. Expect the 4th frame to be
+  // kickstarted.
+  for (int i = 0; i < 3; ++i) {
+    ASSERT_TRUE(ProduceDataChunk(0, 16));
+    PostMojoCallTask_ConsumeDataChunk(0, 16, 16);
+    PostMojoCallTask_SendFrame();
+  }
+  EXPECT_EQ(media::cast::FrameId::first() + 3, WaitForKickstart());
+  EXPECT_EQ(4, NumberOfFramesInFlight());
+
+  // Ack the first two frames and wait for another kickstart (for the 4th frame
+  // again).
+  AckOldestInFlightFrames(2);
+  EXPECT_EQ(2, NumberOfFramesInFlight());
+  EXPECT_EQ(media::cast::FrameId::first() + 3, WaitForKickstart());
+}
+
+TEST_F(CastRemotingSenderTest, CancelsUnsentFrame) {
+  EXPECT_EQ(0u, GetSizeOfNextFrameData());
+  ASSERT_TRUE(ProduceDataChunk(0, 16));
+  PostMojoCallTask_ConsumeDataChunk(0, 16, 16);
+  RunPendingTasks();
+  EXPECT_EQ(16u, GetSizeOfNextFrameData());
+  PostMojoCallTask_CancelInFlightData();
+  RunPendingTasks();
+  EXPECT_EQ(0u, GetSizeOfNextFrameData());
+
+  // Since no frames were sent, none should have been passed to the
+  // CastTransport, and none should have been canceled.
+  std::vector<media::cast::EncodedFrame> frames;
+  TakeSentFrames(&frames);
+  EXPECT_TRUE(frames.empty());
+  EXPECT_TRUE(ExpectNoFramesCanceled());
 }
 
-TEST_F(CastRemotingSenderTest, CancelFramesInFlight) {
-  for (int i = 0; i < 10; ++i)
-    InsertFrame();
+TEST_F(CastRemotingSenderTest, CancelsFramesInFlight) {
+  EXPECT_TRUE(IsFlowControlInRestartingState());
+
+  // Send 10 frames.
+  for (int i = 0; i < 10; ++i) {
+    ASSERT_TRUE(ProduceDataChunk(0, 16));
+    PostMojoCallTask_ConsumeDataChunk(0, 16, 16);
+    PostMojoCallTask_SendFrame();
+  }
+  RunPendingTasks();
+  EXPECT_TRUE(IsFlowControlInConsumingState());
   EXPECT_EQ(10, NumberOfFramesInFlight());
 
-  media::cast::RtcpCastMessage cast_feedback(11);
-  cast_feedback.ack_frame_id = media::cast::FrameId::first();
-  OnReceivedCastMessage(cast_feedback);
+  // Ack the first frame.
+  AckOldestInFlightFrames(1);
+  EXPECT_TRUE(IsFlowControlInConsumingState());
   EXPECT_EQ(9, NumberOfFramesInFlight());
+  EXPECT_TRUE(ExpectFramesCanceled(media::cast::FrameId::first(),
+                                   media::cast::FrameId::first()));
+
+  // Cancel all in-flight data. This should cause the remaining 9 frames to be
+  // canceled.
+  PostMojoCallTask_CancelInFlightData();
+  RunPendingTasks();
+  EXPECT_TRUE(IsFlowControlInRestartingState());
+  EXPECT_EQ(0, NumberOfFramesInFlight());
+  EXPECT_TRUE(ExpectFramesCanceled(media::cast::FrameId::first() + 1,
+                                   media::cast::FrameId::first() + 9));
+
+  // Send one more frame and ack it.
+  ASSERT_TRUE(ProduceDataChunk(0, 16));
+  PostMojoCallTask_ConsumeDataChunk(0, 16, 16);
+  PostMojoCallTask_SendFrame();
+  RunPendingTasks();
+  EXPECT_TRUE(IsFlowControlInConsumingState());
+  EXPECT_EQ(1, NumberOfFramesInFlight());
+  AckOldestInFlightFrames(1);
+  EXPECT_EQ(0, NumberOfFramesInFlight());
+
+  // Check that the dependency metadata was set correctly to indicate a frame
+  // that immediately follows a CancelInFlightData() operation.
+  std::vector<media::cast::EncodedFrame> frames;
+  TakeSentFrames(&frames);
+  ASSERT_EQ(11u, frames.size());
+  for (size_t i = 0; i < 11; ++i) {
+    const media::cast::EncodedFrame& frame = frames[i];
+    EXPECT_EQ(media::cast::FrameId::first() + i, frame.frame_id);
+    if (i == 0 || i == 10)
+      EXPECT_EQ(media::cast::EncodedFrame::KEY, frame.dependency);
+    else
+      EXPECT_EQ(media::cast::EncodedFrame::DEPENDENT, frame.dependency);
+  }
+}
+
+TEST_F(CastRemotingSenderTest, ManagesFlowControl) {
+  EXPECT_TRUE(IsFlowControlInRestartingState());
 
-  CancelFramesInFlight();
+  // Send out a the maximum possible number of unacked frames, but don't ack any
+  // yet.
+  for (int i = 0; i < media::cast::kMaxUnackedFrames; ++i) {
+    ASSERT_TRUE(ProduceDataChunk(0, 4));
+    PostMojoCallTask_ConsumeDataChunk(0, 4, 4);
+    PostMojoCallTask_SendFrame();
+  }
+  RunPendingTasks();
+  EXPECT_TRUE(IsFlowControlInConsumingState());
+  EXPECT_EQ(media::cast::kMaxUnackedFrames, NumberOfFramesInFlight());
+  // Note: All frames should have been sent to the Transport, and so
+  // CastRemotingSender's single-frame data buffer should be empty.
+  EXPECT_EQ(0u, GetSizeOfNextFrameData());
+
+  // Attempting to send the next frame will place the CastRemotingSenderTest in
+  // a "paused flow" state.
+  ASSERT_TRUE(ProduceDataChunk(0, 4));
+  PostMojoCallTask_ConsumeDataChunk(0, 4, 4);
+  PostMojoCallTask_SendFrame();
+  RunPendingTasks();
+  EXPECT_TRUE(IsFlowControlInPausedState());
+  EXPECT_EQ(media::cast::kMaxUnackedFrames, NumberOfFramesInFlight());
+  // Note: The unsent frame resides in CastRemotingSender's single-frame data
+  // buffer.
+  EXPECT_EQ(4u, GetSizeOfNextFrameData());
+
+  // Ack the the first frame and expect sending to resume, starting with the
+  // frame that triggered the pause.
+  AckOldestInFlightFrames(1);
+  EXPECT_TRUE(IsFlowControlInConsumingState());
+  EXPECT_EQ(media::cast::kMaxUnackedFrames, NumberOfFramesInFlight());
+  // Note: The frame causing the earlier pause should have been sent, and so
+  // CastRemotingSender's single-frame data buffer should now be empty.
+  EXPECT_EQ(0u, GetSizeOfNextFrameData());
+
+  // Attempting to send another frame will once again place the
+  // CastRemotingSender in a "paused flow" state.
+  ASSERT_TRUE(ProduceDataChunk(0, 4));
+  PostMojoCallTask_ConsumeDataChunk(0, 4, 4);
+  PostMojoCallTask_SendFrame();
+  RunPendingTasks();
+  EXPECT_TRUE(IsFlowControlInPausedState());
+  EXPECT_EQ(media::cast::kMaxUnackedFrames, NumberOfFramesInFlight());
+  // Note: Once again, CastRemotingSender's single-frame data buffer contains an
+  // unsent frame.
+  EXPECT_EQ(4u, GetSizeOfNextFrameData());
+
+  // Send more frames: Some number of frames will queue-up inside the Mojo data
+  // pipe (the exact number depends on the data pipe's capacity, and how Mojo
+  // manages memory internally). At some point, attempting to produce and push
+  // another frame will fail because the data pipe is full.
+  int num_frames_in_data_pipe = 0;
+  while (ProduceDataChunk(0, 768)) {
+    ++num_frames_in_data_pipe;
+    PostMojoCallTask_ConsumeDataChunk(0, 768, 768);
+    PostMojoCallTask_SendFrame();
+    RunPendingTasks();
+    EXPECT_TRUE(IsFlowControlInPausedState());
+    EXPECT_EQ(media::cast::kMaxUnackedFrames, NumberOfFramesInFlight());
+    // Note: CastRemotingSender's single-frame data buffer should still contain
+    // the unsent 4-byte frame.
+    EXPECT_EQ(4u, GetSizeOfNextFrameData());
+  }
+  EXPECT_LT(0, num_frames_in_data_pipe);
+
+  // Ack one frame at a time until the backlog in the Mojo data pipe has
+  // cleared. In each iteration, the flow will resume, but then it will become
+  // paused again when Mojo method calls are resumed and cause
+  // CastRemotingSender to pull another frame out of the data pipe.
+  int remaining_frames_in_data_pipe = num_frames_in_data_pipe;
+  while (remaining_frames_in_data_pipe > 0) {
+    AckOldestInFlightFrames(1);
+    EXPECT_TRUE(IsFlowControlInConsumingState());
+    EXPECT_EQ(0u, GetSizeOfNextFrameData());
+    // The following will execute one ConsumeDataChunk() and one SendFrame()
+    // Mojo method call.
+    RunPendingTasks();
+    --remaining_frames_in_data_pipe;
+    EXPECT_TRUE(IsFlowControlInPausedState());
+    EXPECT_EQ(media::cast::kMaxUnackedFrames, NumberOfFramesInFlight());
+    EXPECT_EQ(768u, GetSizeOfNextFrameData());
+  }
+
+  // Ack one more frame. This should cause the flow to resume since there are no
+  // longer any frames backlogged on the input side of things.
+  AckOldestInFlightFrames(1);
+  EXPECT_TRUE(IsFlowControlInConsumingState());
+  RunPendingTasks();  // No additional Mojo method calls should be made here.
+  EXPECT_TRUE(IsFlowControlInConsumingState());
+  EXPECT_EQ(media::cast::kMaxUnackedFrames, NumberOfFramesInFlight());
+  EXPECT_EQ(0u, GetSizeOfNextFrameData());
+
+  // Ack all but one frame.
+  AckOldestInFlightFrames(NumberOfFramesInFlight() - 1);
+  EXPECT_TRUE(IsFlowControlInConsumingState());
+  EXPECT_EQ(1, NumberOfFramesInFlight());
+  // ..and one more frame can be sent without pausing.
+  ASSERT_TRUE(ProduceDataChunk(0, 4));
+  PostMojoCallTask_ConsumeDataChunk(0, 4, 4);
+  PostMojoCallTask_SendFrame();
+  RunPendingTasks();
+  EXPECT_TRUE(IsFlowControlInConsumingState());
+  EXPECT_EQ(2, NumberOfFramesInFlight());
+  // ...and ack these last two frames.
+  AckOldestInFlightFrames(2);
+  EXPECT_TRUE(IsFlowControlInConsumingState());
   EXPECT_EQ(0, NumberOfFramesInFlight());
+
+  // Finally, examine all frames that were sent to the CastTransport, and
+  // confirm their metadata and data is valid.
+  std::vector<media::cast::EncodedFrame> frames;
+  TakeSentFrames(&frames);
+  const size_t total_frames_sent =
+      media::cast::kMaxUnackedFrames + 2 + num_frames_in_data_pipe + 1;
+  ASSERT_EQ(total_frames_sent, frames.size());
+  media::cast::RtpTimeTicks last_rtp_timestamp =
+      media::cast::RtpTimeTicks() - media::cast::RtpTimeDelta::FromTicks(1);
+  for (size_t i = 0; i < total_frames_sent; ++i) {
+    const media::cast::EncodedFrame& frame = frames[i];
+    EXPECT_EQ(media::cast::FrameId::first() + i, frame.frame_id);
+    if (i == 0) {
+      EXPECT_EQ(media::cast::EncodedFrame::KEY, frame.dependency);
+      EXPECT_EQ(media::cast::FrameId::first() + i, frame.referenced_frame_id);
+    } else {
+      EXPECT_EQ(media::cast::EncodedFrame::DEPENDENT, frame.dependency);
+      EXPECT_EQ(media::cast::FrameId::first() + i - 1,
+                frame.referenced_frame_id);
+    }
+
+    // RTP timestamp must be monotonically increasing.
+    EXPECT_GT(frame.rtp_timestamp, last_rtp_timestamp);
+    last_rtp_timestamp = frame.rtp_timestamp;
+
+    size_t expected_frame_size = 4;
+    if ((i >= static_cast<size_t>(media::cast::kMaxUnackedFrames + 2)) &&
+        (i < static_cast<size_t>(media::cast::kMaxUnackedFrames + 2 +
+                                 num_frames_in_data_pipe))) {
+      expected_frame_size = 768;
+    }
+    EXPECT_TRUE(ExpectCorrectFrameData(expected_frame_size, frame));
+  }
 }
 
 }  // namespace cast