Reland of "Revert of Update the BWE when the network route changes.

webrtc/modules/congestion_controller/congestion_controller_unittest.cc

 /*
  *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 106 matching lines @@
   EXPECT_CALL(observer_, OnNetworkChanged(0, _, _));
   controller_->SignalNetworkState(kNetworkDown);
 
   EXPECT_CALL(observer_, OnNetworkChanged(kInitialBitrateBps, _, _));
   controller_->SignalNetworkState(kNetworkUp);
 
   EXPECT_CALL(observer_, OnNetworkChanged(0, _, _));
   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
   EXPECT_CALL(*pacer_, ExpectedQueueTimeMs())
       .WillRepeatedly(Return(PacedSender::kMaxQueueLengthMs + 1));
   EXPECT_CALL(observer_, OnNetworkChanged(0, _, _));
   controller_->Process();
 
   // Queue is full and network is down. Expect no bitrate change.
   controller_->SignalNetworkState(kNetworkDown);
@@ skipping 11 matching lines @@
 
   // Let the pacer not be full next time the controller checks.
   EXPECT_CALL(*pacer_, ExpectedQueueTimeMs())
       .WillOnce(Return(PacedSender::kMaxQueueLengthMs - 1));
   EXPECT_CALL(observer_, OnNetworkChanged(kInitialBitrateBps * 2, _, _));
   controller_->Process();
 }
 
 }  // namespace test
 }  // namespace webrtc