Looking up device id by session id for AudioRendererMixerInput

media/audio/audio_manager_base.h

 // Copyright (c) 2012 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.
 
 #ifndef MEDIA_AUDIO_AUDIO_MANAGER_BASE_H_
 #define MEDIA_AUDIO_AUDIO_MANAGER_BASE_H_
 
 #include <string>
 #include <utility>
 
@@ skipping 31 matching lines @@
   // Input device ID used to capture the default system playback stream. When
   // this device ID is passed to MakeAudioInputStream() the returned
   // AudioInputStream will be capturing audio currently being played on the
   // default playback device. At the moment this feature is supported only on
   // some platforms. AudioInputStream::Intialize() will return an error on
   // platforms that don't support it. GetInputStreamParameters() must be used
   // to get the parameters of the loopback device before creating a loopback
   // stream, otherwise stream initialization may fail.
   static const char kLoopbackInputDeviceId[];
 
+  // Returns true if |device_id| corresponds to the default device.
+  static bool IsDefaultDeviceId(const std::string& device_id);
+
   ~AudioManagerBase() override;
 
   // AudioManager:
   scoped_refptr<base::SingleThreadTaskRunner> GetTaskRunner() const override;
   scoped_refptr<base::SingleThreadTaskRunner> GetWorkerTaskRunner() override;
   base::string16 GetAudioInputDeviceModel() override;
   void ShowAudioInputSettings() override;
   void GetAudioInputDeviceNames(AudioDeviceNames* device_names) override;
   void GetAudioOutputDeviceNames(AudioDeviceNames* device_names) override;
   AudioOutputStream* MakeAudioOutputStream(
@@ skipping 122 matching lines @@
 
   // Proxy for creating AudioLog objects.
   AudioLogFactory* const audio_log_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioManagerBase);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_AUDIO_MANAGER_BASE_H_