Add Cast PLI support on sender side.

media/cast/net/rtcp/rtcp_defines.cc

Index: media/cast/net/rtcp/rtcp_defines.cc
diff --git a/media/cast/net/rtcp/rtcp_defines.cc b/media/cast/net/rtcp/rtcp_defines.cc
index b4f363e30a14625b286a94eb5936f840244b57ad..d7b18b9940bda75d9b5f902e8f78a3efb1b0f4e0 100644
--- a/media/cast/net/rtcp/rtcp_defines.cc
+++ b/media/cast/net/rtcp/rtcp_defines.cc
@@ -10,9 +10,15 @@ namespace media {
 namespace cast {
 
 RtcpCastMessage::RtcpCastMessage(uint32_t ssrc)
-    : media_ssrc(ssrc), ack_frame_id(0u), target_delay_ms(0) {}
+    : media_ssrc(ssrc),
+      ack_frame_id(0u),
+      target_delay_ms(0),
+      picture_loss_indicator(false) {}
 RtcpCastMessage::RtcpCastMessage()
-    : media_ssrc(0), ack_frame_id(0u), target_delay_ms(0) {}
+    : media_ssrc(0),
+      ack_frame_id(0u),
+      target_delay_ms(0),
+      picture_loss_indicator(false) {}
 RtcpCastMessage::~RtcpCastMessage() {}
 
 RtcpReceiverEventLogMessage::RtcpReceiverEventLogMessage()