Moved routes tracking to rtp transport controller.

This prepares for eliminating OnNetworkRouteChanged in the Call class.

Bug: webrtc:8415
Change-Id: I62dc7226804e65c90b2a0a771dd6861f6760c8dd
Reviewed-on: https://webrtc-review.googlesource.com/54363
Commit-Queue: Sebastian Jansson <srte@webrtc.org>
Reviewed-by: Stefan Holmer <stefan@webrtc.org>
Reviewed-by: Björn Terelius <terelius@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#22130}
diff --git a/call/rtp_transport_controller_send.cc b/call/rtp_transport_controller_send.cc
index a48d843..71be5cb 100644
--- a/call/rtp_transport_controller_send.cc
+++ b/call/rtp_transport_controller_send.cc
@@ -7,6 +7,7 @@
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
+#include <utility>
 
 #include "call/rtp_transport_controller_send.h"
 #include "rtc_base/logging.h"
@@ -88,21 +89,41 @@
 void RtpTransportControllerSend::OnNetworkRouteChanged(
     const std::string& transport_name,
     const rtc::NetworkRoute& network_route) {
-  BitrateConstraints bitrate_config = bitrate_configurator_.GetConfig();
-  RTC_LOG(LS_INFO) << "Network route changed on transport " << transport_name
-                   << ": new local network id "
-                   << network_route.local_network_id
-                   << " new remote network id "
-                   << network_route.remote_network_id
-                   << " Reset bitrates to min: "
-                   << bitrate_config.min_bitrate_bps
-                   << " bps, start: " << bitrate_config.start_bitrate_bps
-                   << " bps,  max: " << bitrate_config.max_bitrate_bps
-                   << " bps.";
-  RTC_DCHECK_GT(bitrate_config.start_bitrate_bps, 0);
-  send_side_cc_.OnNetworkRouteChanged(
-      network_route, bitrate_config.start_bitrate_bps,
-      bitrate_config.min_bitrate_bps, bitrate_config.max_bitrate_bps);
+  // Check if the network route is connected.
+  if (!network_route.connected) {
+    RTC_LOG(LS_INFO) << "Transport " << transport_name << " is disconnected";
+    // TODO(honghaiz): Perhaps handle this in SignalChannelNetworkState and
+    // consider merging these two methods.
+    return;
+  }
+
+  // Check whether the network route has changed on each transport.
+  auto result =
+      network_routes_.insert(std::make_pair(transport_name, network_route));
+  auto kv = result.first;
+  bool inserted = result.second;
+  if (inserted) {
+    // No need to reset BWE if this is the first time the network connects.
+    return;
+  }
+  if (kv->second != network_route) {
+    kv->second = network_route;
+    BitrateConstraints bitrate_config = bitrate_configurator_.GetConfig();
+    RTC_LOG(LS_INFO) << "Network route changed on transport " << transport_name
+                     << ": new local network id "
+                     << network_route.local_network_id
+                     << " new remote network id "
+                     << network_route.remote_network_id
+                     << " Reset bitrates to min: "
+                     << bitrate_config.min_bitrate_bps
+                     << " bps, start: " << bitrate_config.start_bitrate_bps
+                     << " bps,  max: " << bitrate_config.max_bitrate_bps
+                     << " bps.";
+    RTC_DCHECK_GT(bitrate_config.start_bitrate_bps, 0);
+    send_side_cc_.OnNetworkRouteChanged(
+        network_route, bitrate_config.start_bitrate_bps,
+        bitrate_config.min_bitrate_bps, bitrate_config.max_bitrate_bps);
+  }
 }
 void RtpTransportControllerSend::OnNetworkAvailability(bool network_available) {
   send_side_cc_.SignalNetworkState(network_available ? kNetworkUp