Delete the audio modem and copresence private APIs.

components/audio_modem/test/random_samples.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_TEST_RANDOM_SAMPLES_H_
-#define COMPONENTS_AUDIO_MODEM_TEST_RANDOM_SAMPLES_H_
-
-#include <stddef.h>
-
-#include "base/memory/ref_counted.h"
-
-namespace media {
-class AudioBus;
-class AudioBusRefCounted;
-}
-
-namespace audio_modem {
-
-// Populate random samples given a random seed into the samples array.
-void PopulateSamples(unsigned int random_seed, size_t size, float* samples);
-
-// Create an ref counted audio bus populated with random samples.
-scoped_refptr<media::AudioBusRefCounted>
-    CreateRandomAudioRefCounted(int random_seed, int channels, int samples);
-
-}  // namespace audio_modem
-
-#endif  // COMPONENTS_AUDIO_MODEM_TEST_RANDOM_SAMPLES_H_