Add Cast PLI support on sender side.

chrome/common/cast_messages.h

Index: chrome/common/cast_messages.h
diff --git a/chrome/common/cast_messages.h b/chrome/common/cast_messages.h
index 52a642a1339c5c0225976f817fa5c9c9f9071e86..f0e6fa6c5c78d1182961028a4f186271e0abf082 100644
--- a/chrome/common/cast_messages.h
+++ b/chrome/common/cast_messages.h
@@ -97,12 +97,16 @@ IPC_STRUCT_TRAITS_BEGIN(media::cast::FrameEvent)
 IPC_STRUCT_TRAITS_END()
 
 IPC_STRUCT_TRAITS_BEGIN(media::cast::RtcpCastMessage)
-  IPC_STRUCT_TRAITS_MEMBER(media_ssrc)
+  IPC_STRUCT_TRAITS_MEMBER(remote_ssrc)
   IPC_STRUCT_TRAITS_MEMBER(ack_frame_id)
   IPC_STRUCT_TRAITS_MEMBER(target_delay_ms)
   IPC_STRUCT_TRAITS_MEMBER(missing_frames_and_packets)
 IPC_STRUCT_TRAITS_END()
 
+IPC_STRUCT_TRAITS_BEGIN(media::cast::RtcpPliMessage)
+  IPC_STRUCT_TRAITS_MEMBER(remote_ssrc)
+IPC_STRUCT_TRAITS_END()
+
 IPC_STRUCT_TRAITS_BEGIN(media::cast::RtcpEvent)
   IPC_STRUCT_TRAITS_MEMBER(type)
   IPC_STRUCT_TRAITS_MEMBER(timestamp)
@@ -135,14 +139,19 @@ IPC_MESSAGE_CONTROL2(CastMsg_ReceivedPacket,
 
 IPC_MESSAGE_CONTROL3(CastMsg_Rtt,
                      int32_t /* channel_id */,
-                     uint32_t /* ssrc */,
+                     uint32_t /* rtp sender ssrc */,
                      base::TimeDelta /* rtt */)
 
 IPC_MESSAGE_CONTROL3(CastMsg_RtcpCastMessage,
                      int32_t /* channel_id */,
-                     uint32_t /* ssrc */,
+                     uint32_t /* rtp sender ssrc */,
                      media::cast::RtcpCastMessage /* cast_message */)
 
+// This message indicates receiving picture loss indicator from rtp receiver.
+IPC_MESSAGE_CONTROL2(CastMsg_Pli,
+                     int32_t /* channel_id */,
+                     uint32_t /* rtp sender ssrc */)
+
 IPC_MESSAGE_CONTROL2(CastMsg_NotifyStatusChange,
                      int32_t /* channel_id */,
                      media::cast::CastTransportStatus /* status */)
@@ -212,6 +221,10 @@ IPC_MESSAGE_CONTROL3(CastHostMsg_AddCastFeedback,
                      media::cast::RtcpCastMessage /* cast message */,
                      base::TimeDelta /* target delay */)
 
+IPC_MESSAGE_CONTROL2(CastHostMsg_AddPli,
+                     int32_t /* channel id */,
+                     media::cast::RtcpPliMessage /* pli message */)
+
 IPC_MESSAGE_CONTROL2(
     CastHostMsg_AddRtcpEvents,
     int32_t /* channel id */,