Reland of Delete class SSRCDatabase, and its global ssrc registry.

webrtc/modules/rtp_rtcp/source/rtp_rtcp_impl.cc

Index: webrtc/modules/rtp_rtcp/source/rtp_rtcp_impl.cc
diff --git a/webrtc/modules/rtp_rtcp/source/rtp_rtcp_impl.cc b/webrtc/modules/rtp_rtcp/source/rtp_rtcp_impl.cc
index f74ebba0c0e12b09f96a57cc67795fd4054d1de6..1bf2caefad843454b7dfe5c997e979e87dd6ff3a 100644
--- a/webrtc/modules/rtp_rtcp/source/rtp_rtcp_impl.cc
+++ b/webrtc/modules/rtp_rtcp/source/rtp_rtcp_impl.cc
@@ -100,7 +100,6 @@ ModuleRtpRtcpImpl::ModuleRtpRtcpImpl(const Configuration& configuration)
                      this),
       clock_(configuration.clock),
       audio_(configuration.audio),
-      collision_detected_(false),
       last_process_time_(configuration.clock->TimeInMilliseconds()),
       last_bitrate_process_time_(configuration.clock->TimeInMilliseconds()),
       last_rtt_process_time_(configuration.clock->TimeInMilliseconds()),
@@ -112,11 +111,6 @@ ModuleRtpRtcpImpl::ModuleRtpRtcpImpl(const Configuration& configuration)
       remote_bitrate_(configuration.remote_bitrate_estimator),
       rtt_stats_(configuration.rtt_stats),
       rtt_ms_(0) {
-  // Make sure that RTCP objects are aware of our SSRC.
-  uint32_t SSRC = rtp_sender_.SSRC();
-  rtcp_sender_.SetSSRC(SSRC);
-  SetRtcpReceiverSsrcs(SSRC);
-
   // Make sure rtcp sender use same timestamp offset as rtp sender.
   rtcp_sender_.SetTimestampOffset(rtp_sender_.TimestampOffset());
 
@@ -310,7 +304,6 @@ uint32_t ModuleRtpRtcpImpl::SSRC() const {
   return rtp_sender_.SSRC();
 }
 
-// Configure SSRC, default is a random number.
 void ModuleRtpRtcpImpl::SetSSRC(const uint32_t ssrc) {
   rtp_sender_.SetSSRC(ssrc);
   rtcp_sender_.SetSSRC(ssrc);
@@ -355,19 +348,11 @@ int32_t ModuleRtpRtcpImpl::SetSendingStatus(const bool sending) {
     if (rtcp_sender_.SetSendingStatus(GetFeedbackState(), sending) != 0) {
       LOG(LS_WARNING) << "Failed to send RTCP BYE";
     }
-
-    collision_detected_ = false;
-
-    // Generate a new SSRC for the next "call" if false
-    rtp_sender_.SetSendingStatus(sending);
-
-    // Make sure that RTCP objects are aware of our SSRC (it could have changed
-    // Due to collision)
-    uint32_t SSRC = rtp_sender_.SSRC();
-    rtcp_sender_.SetSSRC(SSRC);
-    SetRtcpReceiverSsrcs(SSRC);
-
-    return 0;
+    if (sending) {
+      // Update Rtcp receiver config, to track Rtx config changes from
+      // the SetRtxStatus and SetRtxSsrc methods.
+      SetRtcpReceiverSsrcs(rtp_sender_.SSRC());
+    }
   }
   return 0;
 }
@@ -794,24 +779,6 @@ void ModuleRtpRtcpImpl::SetRemoteSSRC(const uint32_t ssrc) {
   // Inform about the incoming SSRC.
   rtcp_sender_.SetRemoteSSRC(ssrc);
   rtcp_receiver_.SetRemoteSSRC(ssrc);
-
-  // Check for a SSRC collision.
-  if (rtp_sender_.SSRC() == ssrc && !collision_detected_) {
-    // If we detect a collision change the SSRC but only once.
-    collision_detected_ = true;
-    uint32_t new_ssrc = rtp_sender_.GenerateNewSSRC();
-    if (new_ssrc == 0) {
-      // Configured via API ignore.
-      return;
-    }
-    if (RtcpMode::kOff != rtcp_sender_.Status()) {
-      // Send RTCP bye on the current SSRC.
-      SendRTCP(kRtcpBye);
-    }
-    // Change local SSRC and inform all objects about the new SSRC.
-    rtcp_sender_.SetSSRC(new_ssrc);
-    SetRtcpReceiverSsrcs(new_ssrc);
-  }
 }
 
 void ModuleRtpRtcpImpl::BitrateSent(uint32_t* total_rate,