Make a the decisions of ANA optional for the opus encoder.

webrtc/modules/audio_coding/codecs/opus/audio_encoder_opus_unittest.cc

 /*
  *  Copyright (c) 2015 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 425 matching lines @@
   EXPECT_EQ(rtc::Optional<int>(8), config.GetNewComplexity());
 
   // Bitrate within hysteresis window. Expect empty output.
   config.bitrate_bps = rtc::Optional<int>(12500);
   EXPECT_EQ(rtc::Optional<int>(), config.GetNewComplexity());
 
   // Bitrate above hysteresis window. Expect lower complexity.
   config.bitrate_bps = rtc::Optional<int>(14001);
   EXPECT_EQ(rtc::Optional<int>(6), config.GetNewComplexity());
 }
+
+TEST(AudioEncoderOpusTest, EmptyConfigDontAffectEncoderSettings) {

[ivoc, 2016/12/27 13:56:56]

nit: Please rename to EmptyConfigDoesntAffectEncoderSettings.

+  auto states = CreateCodec(2);
+  states.encoder->EnableAudioNetworkAdaptor("", nullptr);
+
+  auto config = CreateEncoderRuntimeConfig();
+  AudioNetworkAdaptor::EncoderRuntimeConfig empty_config;
+
+  EXPECT_CALL(**states.mock_audio_network_adaptor, GetEncoderRuntimeConfig())
+      .WillOnce(Return(config))
+      .WillOnce(Return(empty_config));
+
+  constexpr size_t kOverhead = 64;
+  EXPECT_CALL(**states.mock_audio_network_adaptor, SetOverhead(kOverhead))
+      .Times(2);
+  states.encoder->OnReceivedOverhead(kOverhead);
+  states.encoder->OnReceivedOverhead(kOverhead);
+
+  CheckEncoderRuntimeConfig(states.encoder.get(), config);
+}
+
 }  // namespace webrtc