Parse FlexFEC RTP headers in Call and add integration with BWE.

webrtc/modules/rtp_rtcp/source/rtp_packet.cc

Index: webrtc/modules/rtp_rtcp/source/rtp_packet.cc
diff --git a/webrtc/modules/rtp_rtcp/source/rtp_packet.cc b/webrtc/modules/rtp_rtcp/source/rtp_packet.cc
index b7d71c27898cbb8abf7e860e65736df6377eb125..e720eebc4aff88a9d0242a07c3017048f4adfb99 100644
--- a/webrtc/modules/rtp_rtcp/source/rtp_packet.cc
+++ b/webrtc/modules/rtp_rtcp/source/rtp_packet.cc
@@ -86,6 +86,10 @@ bool Packet::Parse(const uint8_t* buffer, size_t buffer_size) {
   return true;
 }
 
+bool Packet::Parse(rtc::ArrayView<const uint8_t> packet) {
+  return Parse(packet.data(), packet.size());
+}
+
 bool Packet::Parse(rtc::CopyOnWriteBuffer buffer) {
   if (!ParseBuffer(buffer.cdata(), buffer.size())) {
     Clear();