Fixing video loopback test with encoder factory.

BUG=webrtc:5806

Review-Url: https://codereview.webrtc.org/2870123002
Cr-Commit-Position: refs/heads/master@{#18079}
diff --git a/webrtc/audio/audio_send_stream.cc b/webrtc/audio/audio_send_stream.cc
index d413a96..e95c5e7 100644
--- a/webrtc/audio/audio_send_stream.cc
+++ b/webrtc/audio/audio_send_stream.cc
@@ -388,6 +388,8 @@
                                      const Config& new_config) {
   RTC_DCHECK(new_config.send_codec_spec);
   const auto& spec = *new_config.send_codec_spec;
+
+  RTC_DCHECK(new_config.encoder_factory);
   std::unique_ptr<AudioEncoder> encoder =
       new_config.encoder_factory->MakeAudioEncoder(spec.payload_type,
                                                    spec.format);
diff --git a/webrtc/video/video_quality_test.cc b/webrtc/video/video_quality_test.cc
index b554170..86d61d6 100644
--- a/webrtc/video/video_quality_test.cc
+++ b/webrtc/video/video_quality_test.cc
@@ -1736,7 +1736,7 @@
            {"OPUS", 48000, 2,
             {{"usedtx", (params_.audio.dtx ? "1" : "0")},
               {"stereo", "1"}}}});
-
+  audio_send_config_.encoder_factory = encoder_factory_;
   audio_send_stream_ = call->CreateAudioSendStream(audio_send_config_);
 
   AudioReceiveStream::Config audio_config;