Delete the audio modem and copresence private APIs.

components/audio_modem/public/modem.h

-// Copyright 2015 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 COMPONENTS_AUDIO_MODEM_PUBLIC_MODEM_H_
-#define COMPONENTS_AUDIO_MODEM_PUBLIC_MODEM_H_
-
-#include <memory>
-#include <string>
-
-#include "components/audio_modem/public/audio_modem_types.h"
-
-namespace audio_modem {
-
-class WhispernetClient;
-
-class Modem {
- public:
-  virtual ~Modem() {}
-
-  // Initializes the object. Do not use this object before calling this method.
-  virtual void Initialize(WhispernetClient* client,
-                          const TokensCallback& tokens_cb) = 0;
-
-  virtual void StartPlaying(AudioType type) = 0;
-  virtual void StopPlaying(AudioType type) = 0;
-
-  virtual void StartRecording(AudioType type) = 0;
-  virtual void StopRecording(AudioType type) = 0;
-
-  virtual void SetToken(AudioType type,
-                        const std::string& url_safe_token) = 0;
-
-  virtual const std::string GetToken(AudioType type) const = 0;
-
-  virtual bool IsPlayingTokenHeard(AudioType type) const = 0;
-
-  virtual void SetTokenParams(AudioType type,
-                              const TokenParameters& params) = 0;
-
-  static std::unique_ptr<Modem> Create();
-};
-
-}  // namespace audio_modem
-
-#endif  // COMPONENTS_AUDIO_MODEM_PUBLIC_MODEM_H_