Add Cast PLI support on sender side.

media/cast/net/rtcp/rtcp_utility.cc

Index: media/cast/net/rtcp/rtcp_utility.cc
diff --git a/media/cast/net/rtcp/rtcp_utility.cc b/media/cast/net/rtcp/rtcp_utility.cc
index 74af3a04fb45ab8b3998c185d80cafdcda4e49a4..be2b3eb85a6b2ca492e6570908465f14cd85ef64 100644
--- a/media/cast/net/rtcp/rtcp_utility.cc
+++ b/media/cast/net/rtcp/rtcp_utility.cc
@@ -33,7 +33,8 @@ RtcpParser::RtcpParser(uint32_t local_ssrc, uint32_t remote_ssrc)
       has_sender_report_(false),
       has_last_report_(false),
       has_cast_message_(false),
-      has_receiver_reference_time_report_(false) {}
+      has_receiver_reference_time_report_(false),
+      has_picture_loss_indicator_(false) {}
 
 RtcpParser::~RtcpParser() {}
 
@@ -45,6 +46,7 @@ bool RtcpParser::Parse(base::BigEndianReader* reader) {
   receiver_log_.clear();
   has_cast_message_ = false;
   has_receiver_reference_time_report_ = false;
+  has_picture_loss_indicator_ = false;
 
   while (reader->remaining()) {
     RtcpCommonHeader header;
@@ -72,10 +74,13 @@ bool RtcpParser::Parse(base::BigEndianReader* reader) {
           return false;
         break;
 
-      case kPacketTypePayloadSpecific:
+      case kPacketTypePayloadSpecific: {
         if (!ParseFeedbackCommon(&chunk, header))
           return false;
+        if (!ParsePli(&chunk, header))
+          return false;
         break;
+      }
 
       case kPacketTypeXr:
         if (!ParseExtendedReport(&chunk, header))
@@ -184,6 +189,30 @@ bool RtcpParser::ParseReportBlock(base::BigEndianReader* reader) {
   return true;
 }
 
+bool RtcpParser::ParsePli(base::BigEndianReader* reader,
+                          const RtcpCommonHeader& header) {
+  if (header.IC != 1)
+    return true;
+
+  uint32_t receiver_ssrc, sender_ssrc;
+  if (!reader->ReadU32(&receiver_ssrc))
+    return false;
+
+  // Ignore this Rtcp if the receiver ssrc does not match.
+  if (receiver_ssrc != remote_ssrc_)
+    return true;
+
+  if (!reader->ReadU32(&sender_ssrc))
+    return false;
+
+  // Ignore this Rtcp if the sender ssrc does not match.
+  if (sender_ssrc != local_ssrc_)
+    return true;
+
+  has_picture_loss_indicator_ = true;
+  return true;
+}
+
 bool RtcpParser::ParseApplicationDefined(base::BigEndianReader* reader,
                                          const RtcpCommonHeader& header) {
   uint32_t sender_ssrc;