Fix Chromium style checker warnings for MockAudioDecoder

BUG=webrtc:5805

Review-Url: https://codereview.webrtc.org/2934143003
Cr-Commit-Position: refs/heads/master@{#18587}

webrtc/pc/BUILD.gn

@@ -389,6 +389,7 @@ if (rtc_include_tests) {
       "../media:rtc_media_tests_utils",
       "../pc:rtc_pc",
       "../system_wrappers:metrics_default",
+      "../test:audio_codec_mocks",
       "//testing/gmock",
     ]
 

webrtc/test/BUILD.gn

@@ -581,6 +581,7 @@ rtc_source_set("test_renderer") {
 rtc_source_set("audio_codec_mocks") {
   testonly = true
   sources = [
+    "mock_audio_decoder.cc",
     "mock_audio_decoder.h",
     "mock_audio_decoder_factory.h",
     "mock_audio_encoder.cc",

webrtc/test/mock_audio_decoder.cc

@@ -0,0 +1,20 @@
+/*
+ *  Copyright (c) 2017 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.
+ */
+
+#include "webrtc/test/mock_audio_decoder.h"
+
+namespace webrtc {
+
+MockAudioDecoder::MockAudioDecoder() = default;
+MockAudioDecoder::~MockAudioDecoder() {
+  Die();
+}
+
+}  // namespace webrtc

webrtc/test/mock_audio_decoder.h

@@ -18,8 +18,8 @@ namespace webrtc {
 
 class MockAudioDecoder : public AudioDecoder {
  public:
-  MockAudioDecoder() {}
-  virtual ~MockAudioDecoder() { Die(); }
+  MockAudioDecoder();
+  ~MockAudioDecoder();
   MOCK_METHOD0(Die, void());
   MOCK_METHOD5(DecodeInternal,
                int(const uint8_t*, size_t, int, int16_t*, SpeechType*));