Switching AudioInputDeviceManager from using AudioManager interface to AudioSystem one.

media/audio/audio_system.cc

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "media/audio/audio_system.h"
+#include "base/single_thread_task_runner.h"
 
 namespace media {
 
 static AudioSystem* g_last_created = nullptr;
 
+void AudioSystem::OnAudioThreadDeleter::operator()(
+    const AudioSystem* instance) const {
+  CHECK(instance);
+  AudioSystem::ClearInstance(instance);
+
+  if (instance->GetTaskRunner()->BelongsToCurrentThread()) {
+    delete instance;
+    return;
+  }
+  if (!instance->GetTaskRunner()->DeleteSoon(FROM_HERE, instance)) {
+    LOG(WARNING) << "Failed to delete AudioManager instance.";
+  }
+}
+
 AudioSystem::~AudioSystem() {}
 
 AudioSystem* AudioSystem::Get() {
   return g_last_created;
 }
 
 void AudioSystem::SetInstance(AudioSystem* audio_system) {
   DCHECK(audio_system);
   if (g_last_created && audio_system) {
     // We create multiple instances of AudioSystem only when testing.
     // We should not encounter this case in production.
     LOG(WARNING) << "Multiple instances of AudioSystem detected";
   }
   g_last_created = audio_system;
 }
 
 void AudioSystem::ClearInstance(const AudioSystem* audio_system) {
   DCHECK(audio_system);
   if (g_last_created != audio_system) {
     // We create multiple instances of AudioSystem only when testing.
     // We should not encounter this case in production.
     LOG(WARNING) << "Multiple instances of AudioSystem detected";
   } else {
     g_last_created = nullptr;
   }
 }
 
 }  // namespace media