Update the BWE when the network route changes.

webrtc/modules/congestion_controller/congestion_controller_unittest.cc

Index: webrtc/modules/congestion_controller/congestion_controller_unittest.cc
diff --git a/webrtc/modules/congestion_controller/congestion_controller_unittest.cc b/webrtc/modules/congestion_controller/congestion_controller_unittest.cc
index c82c75daf3cdd5f6f794cb26a5f715947d02ba3d..1a265824bc4784b5fbbf2db8ee930bc29dc1a02d 100644
--- a/webrtc/modules/congestion_controller/congestion_controller_unittest.cc
+++ b/webrtc/modules/congestion_controller/congestion_controller_unittest.cc
@@ -124,6 +124,20 @@ TEST_F(CongestionControllerTest, SignalNetworkState) {
   controller_->SignalNetworkState(kNetworkDown);
 }
 
+TEST_F(CongestionControllerTest, ResetBweAndBitrates) {
+  int new_bitrate = 200000;
+  EXPECT_CALL(observer_, OnNetworkChanged(new_bitrate, _, _));
+  EXPECT_CALL(*pacer_, SetEstimatedBitrate(new_bitrate));
+  controller_->ResetBweAndBitrates(new_bitrate, -1, -1);
+
+  // If the bitrate is reset to -1, the new starting bitrate will be
+  // the minimum default bitrate 10000bps.
+  int min_default_bitrate = 10000;
+  EXPECT_CALL(observer_, OnNetworkChanged(min_default_bitrate, _, _));
+  EXPECT_CALL(*pacer_, SetEstimatedBitrate(min_default_bitrate));
+  controller_->ResetBweAndBitrates(-1, -1, -1);
+}
+
 TEST_F(CongestionControllerTest,
        SignalNetworkStateAndQueueIsFullAndEstimateChange) {
   // Send queue is full