Test and fix for huge bwe drop after alr state.

webrtc/audio/test/low_bandwidth_audio_test.cc

Index: webrtc/audio/test/low_bandwidth_audio_test.cc
diff --git a/webrtc/audio/test/low_bandwidth_audio_test.cc b/webrtc/audio/test/low_bandwidth_audio_test.cc
index 070253e0a171b389663872f69ee6a5bdbfc18ac9..abf0b2a270acc38a86d919c782ab05ade9e838bc 100644
--- a/webrtc/audio/test/low_bandwidth_audio_test.cc
+++ b/webrtc/audio/test/low_bandwidth_audio_test.cc
@@ -11,12 +11,20 @@
 #include <algorithm>
 
 #include "gflags/gflags.h"
+
 #include "webrtc/audio/test/low_bandwidth_audio_test.h"
+#include "webrtc/base/ptr_util.h"
 #include "webrtc/common_audio/wav_file.h"
-#include "webrtc/test/gtest.h"
+#include "webrtc/logging/rtc_event_log/mock/mock_rtc_event_log.h"
 #include "webrtc/system_wrappers/include/sleep.h"
+#include "webrtc/test/field_trial.h"
+#include "webrtc/test/gmock.h"
+#include "webrtc/test/gtest.h"
 #include "webrtc/test/testsupport/fileutils.h"
 
+using ::testing::NiceMock;
+using ::testing::Invoke;
+using ::testing::_;
 
 DEFINE_int32(sample_rate_hz, 16000,
              "Sample rate (Hz) of the produced audio files.");
@@ -26,7 +34,6 @@ DEFINE_bool(quick, false,
             "Used to quickly check that the test runs without crashing.");
 
 namespace {
-
 // Wait half a second between stopping sending and stopping receiving audio.
 constexpr int kExtraRecordTimeMs = 500;
 
@@ -87,6 +94,7 @@ FakeNetworkPipe::Config AudioQualityTest::GetNetworkPipeConfig() {
 
 test::PacketTransport* AudioQualityTest::CreateSendTransport(
     Call* sender_call) {
+  sender_call_ = sender_call;
   return new test::PacketTransport(
       sender_call, this, test::PacketTransport::kSender,
       test::CallTest::payload_type_map_, GetNetworkPipeConfig());
@@ -110,6 +118,8 @@ void AudioQualityTest::ModifyAudioConfigs(
 }
 
 void AudioQualityTest::PerformTest() {
+  sender_call_->OnTransportOverheadChanged(webrtc::MediaType::AUDIO, 0);
+
   if (FLAGS_quick) {
     // Let the recording run for a small amount of time to check if it works.
     SleepMs(1000);
@@ -168,5 +178,67 @@ TEST_F(LowBandwidthAudioTest, Mobile2GNetwork) {
   RunBaseTest(&test);
 }
 
+class NoBandwidthDropAfterDTX : public AudioQualityTest {
+  void ModifyAudioConfigs(
+      AudioSendStream::Config* send_config,
+      std::vector<AudioReceiveStream::Config>* receive_configs) override {
+    send_config->send_codec_spec =
+        rtc::Optional<AudioSendStream::Config::SendCodecSpec>(
+            {test::CallTest::kAudioSendPayloadType,
+             {"OPUS",
+              48000,
+              2,
+              {{"ptime", "60"}, {"usedtx", "1"}, {"stereo", "1"}}}});
+
+    send_config->min_bitrate_bps = 6000;
+    send_config->max_bitrate_bps = 100000;
+    send_config->rtp.extensions.push_back(
+        RtpExtension(RtpExtension::kTransportSequenceNumberUri,
+                     kTransportSequenceNumberExtensionId));
+    for (AudioReceiveStream::Config& recv_config : *receive_configs) {
+      recv_config.rtp.transport_cc = true;
+      recv_config.rtp.extensions = send_config->rtp.extensions;
+      recv_config.rtp.remote_ssrc = send_config->rtp.ssrc;
+    }
+  }
+
+  std::string AudioInputFile() override {
+    return test::ResourcePath("voice_engine/audio_dtx16", "wav");
+  }
+
+  void LogDelayBasedBweUpdate(int32_t bitrate_bps,
+                              BandwidthUsage detector_state) {
+    EXPECT_GE(bitrate_bps, 30000);
+  }
+
+  Call::Config GetSenderCallConfig() override {
+    EXPECT_CALL(mock_event_log_, LogDelayBasedBweUpdate(_, _))
+        .WillRepeatedly(
+            Invoke(this, &NoBandwidthDropAfterDTX::LogDelayBasedBweUpdate));
+
+    Call::Config call_config(&mock_event_log_);
+    return call_config;
+  }
+
+  FakeNetworkPipe::Config GetNetworkPipeConfig() override {
+    FakeNetworkPipe::Config pipe_config;
+    pipe_config.link_capacity_kbps = 50;
+    pipe_config.queue_length_packets = 1500;
+    pipe_config.queue_delay_ms = 300;
+    return pipe_config;
+  }
+
+ private:
+  NiceMock<MockRtcEventLog> mock_event_log_;
+};
+
+TEST_F(LowBandwidthAudioTest, NoBandwidthDropAfterDTX) {
+  webrtc::test::ScopedFieldTrials override_field_trials(
+      "/WebRTC-Audio-SendSideBwe/Enabled"
+      "/WebRTC-SendSideBwe-WithOverhead/Enabled/");
+  NoBandwidthDropAfterDTX test;
+  RunBaseTest(&test);
+}
+
 }  // namespace test
 }  // namespace webrtc