Add Cast PLI support on sender side.

media/cast/sender/video_sender_unittest.cc

Index: media/cast/sender/video_sender_unittest.cc
diff --git a/media/cast/sender/video_sender_unittest.cc b/media/cast/sender/video_sender_unittest.cc
index 3d315ea2199d91c8cfc671391b4c4187cae9cb4c..3cedc6cb8e39f721f7e35a5dbab11a81df139bb1 100644
--- a/media/cast/sender/video_sender_unittest.cc
+++ b/media/cast/sender/video_sender_unittest.cc
@@ -124,6 +124,7 @@ class PeerVideoSender : public VideoSender {
                     transport_sender,
                     base::Bind(&IgnorePlayoutDelayChanges)) {}
   using VideoSender::OnReceivedCastFeedback;
+  using VideoSender::OnReceivedPli;
 };
 
 class TransportClient : public CastTransportSender::Client {
@@ -602,5 +603,41 @@ TEST_F(VideoSenderTest, PopulatesResourceUtilizationInFrameMetadata) {
   }
 }
 
+TEST_F(VideoSenderTest, CancelSendingOnReceivingPli) {
+  InitEncoder(false, true);
+  ASSERT_EQ(STATUS_INITIALIZED, operational_status_);
+
+  // Send a frame and ACK it.
+  scoped_refptr<media::VideoFrame> video_frame = GetNewVideoFrame();
+  video_sender_->InsertRawVideoFrame(video_frame, testing_clock_->NowTicks());
+  RunTasks(33);
+
+  RtcpCastMessage cast_feedback(1);
+  cast_feedback.media_ssrc = 2;
+  cast_feedback.ack_frame_id = 0;
+  video_sender_->OnReceivedCastFeedback(cast_feedback);
+  EXPECT_EQ(1, transport_->number_of_rtp_packets());
+
+  transport_->SetPause(true);
+  // Send three more frames.
+  for (int i = 0; i < 3; i++) {
+    video_frame = GetNewVideoFrame();
+    video_sender_->InsertRawVideoFrame(video_frame, testing_clock_->NowTicks());
+    RunTasks(33);
+  }
+

[Irfan, 2016/02/29 16:01:23]

do we need an EXPECT_EQ on how many RTP packets we expect before they get
cancelled ?

[xjz, 2016/02/29 19:48:59]

This check was done on Line 619 before paused the transport. Moved it here to
make it more obvious.

+  // Frames should be in buffer, waiting.
+  // Received PLI from receiver.
+  video_sender_->OnReceivedPli();
+  video_frame = GetNewVideoFrame();
+  video_sender_->InsertRawVideoFrame(
+      video_frame,
+      testing_clock_->NowTicks() + base::TimeDelta::FromMilliseconds(500));
+  RunTasks(33);
+  transport_->SetPause(false);
+  RunTasks(33);
+  EXPECT_EQ(2, transport_->number_of_rtp_packets());
+}
+
 }  // namespace cast
 }  // namespace media