Switching VirtualKeyboardPrivate keyboard config call stack to receive HasInputDevices() responce a…

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"
+
+namespace media {
+
+static AudioSystem* g_last_created = nullptr;
+
+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