Switch to using new ACM methods for encoder management

webrtc/modules/audio_coding/acm2/rent_a_codec.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 245 matching lines @@
   for (const CodecInst& ci : RentACodec::Database()) {
     RentACodec::RegisterCngPayloadType(&cng_payload_types, ci);
     RentACodec::RegisterRedPayloadType(&red_payload_types, ci);
   }
 }
 
 RentACodec::StackParameters::~StackParameters() = default;
 
 std::unique_ptr<AudioEncoder> RentACodec::RentEncoderStack(
     StackParameters* param) {
-  RTC_DCHECK(param->speech_encoder);
+  if (!param->speech_encoder)
+    return nullptr;
 
   if (param->use_codec_fec) {
     // Switch FEC on. On failure, remember that FEC is off.
     if (!param->speech_encoder->SetFec(true))
       param->use_codec_fec = false;
   } else {
     // Switch FEC off. This shouldn't fail.
     const bool success = param->speech_encoder->SetFec(false);
     RTC_DCHECK(success);
   }
@@ skipping 25 matching lines @@
   }
   return encoder_stack;
 }
 
 std::unique_ptr<AudioDecoder> RentACodec::RentIsacDecoder() {
   return CreateIsacDecoder(isac_bandwidth_info_);
 }
 
 }  // namespace acm2
 }  // namespace webrtc