Add Cast PLI support on sender side.

chrome/renderer/media/cast_transport_sender_ipc.h

Index: chrome/renderer/media/cast_transport_sender_ipc.h
diff --git a/chrome/renderer/media/cast_transport_sender_ipc.h b/chrome/renderer/media/cast_transport_sender_ipc.h
index 2903d3169b1675c6b8d7c64a77a7d003a6df9da2..db7c09179710b770453f34e2245b23abcd6f8294 100644
--- a/chrome/renderer/media/cast_transport_sender_ipc.h
+++ b/chrome/renderer/media/cast_transport_sender_ipc.h
@@ -37,11 +37,13 @@ class CastTransportSenderIPC
   void InitializeAudio(
       const media::cast::CastTransportRtpConfig& config,
       const media::cast::RtcpCastMessageCallback& cast_message_cb,
-      const media::cast::RtcpRttCallback& rtt_cb) override;
+      const media::cast::RtcpRttCallback& rtt_cb,
+      const media::cast::RtcpPliCallback& pli_cb) override;
   void InitializeVideo(
       const media::cast::CastTransportRtpConfig& config,
       const media::cast::RtcpCastMessageCallback& cast_message_cb,
-      const media::cast::RtcpRttCallback& rtt_cb) override;
+      const media::cast::RtcpRttCallback& rtt_cb,
+      const media::cast::RtcpPliCallback& pli_cb) override;
   void InsertFrame(uint32_t ssrc,
                    const media::cast::EncodedFrame& frame) override;
   void SendSenderReport(
@@ -71,6 +73,7 @@ class CastTransportSenderIPC
   void OnRtt(uint32_t ssrc, base::TimeDelta rtt);
   void OnRtcpCastMessage(uint32_t ssrc,
                          const media::cast::RtcpCastMessage& cast_message);
+  void OnReceivedPli(uint32_t ssrc);
   void OnReceivedPacket(const media::cast::Packet& packet);
 
  private:
@@ -80,6 +83,7 @@ class CastTransportSenderIPC
 
     media::cast::RtcpCastMessageCallback cast_message_cb;
     media::cast::RtcpRttCallback rtt_cb;
+    media::cast::RtcpPliCallback pli_cb;
   };
 
   void Send(IPC::Message* message);