Switching MediaStreamsManager from using AudioManager interface to AudioSystem one.

media/audio/mock_audio_manager.h

Index: media/audio/mock_audio_manager.h
diff --git a/media/audio/mock_audio_manager.h b/media/audio/mock_audio_manager.h
index a75e940c34a53ca0bc85f3cbbff9e71e69501f42..69e0d1496ed022a37cd159da08c1bd7c09d73662 100644
--- a/media/audio/mock_audio_manager.h
+++ b/media/audio/mock_audio_manager.h
@@ -5,6 +5,7 @@
 #ifndef MEDIA_AUDIO_MOCK_AUDIO_MANAGER_H_
 #define MEDIA_AUDIO_MOCK_AUDIO_MANAGER_H_
 
+#include "base/callback.h"
 #include "base/macros.h"
 #include "base/sequenced_task_runner_helpers.h"
 #include "media/audio/audio_manager.h"
@@ -23,6 +24,8 @@ class MockAudioManager : public AudioManager {
   };
 
   using UniquePtr = std::unique_ptr<MockAudioManager, Deleter>;
+  using GetDeviceDescriptionsCallback =
+      base::RepeatingCallback<void(AudioDeviceDescriptions*)>;
 
   explicit MockAudioManager(
       scoped_refptr<base::SingleThreadTaskRunner> task_runner);
@@ -83,6 +86,10 @@ class MockAudioManager : public AudioManager {
   void SetDefaultOutputStreamParameters(const AudioParameters& params);
   void SetHasInputDevices(bool has_input_devices);
   void SetHasOutputDevices(bool has_output_devices);
+  void SetInputDeviceDescriptionsCallback(
+      GetDeviceDescriptionsCallback callback);
+  void SetOutputDeviceDescriptionsCallback(
+      GetDeviceDescriptionsCallback callback);
 
  protected:
   ~MockAudioManager() override;
@@ -95,6 +102,8 @@ class MockAudioManager : public AudioManager {
   AudioParameters default_output_params_;
   bool has_input_devices_ = true;
   bool has_output_devices_ = true;
+  GetDeviceDescriptionsCallback get_input_device_descriptions_cb_;
+  GetDeviceDescriptionsCallback get_output_device_descriptions_cb_;
 
   DISALLOW_COPY_AND_ASSIGN(MockAudioManager);
 };