Delete the audio modem and copresence private APIs.

components/audio_modem/test/random_samples.cc

-// 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.
-
-#include "components/audio_modem/test/random_samples.h"
-
-#include <cstdlib>
-
-#include "build/build_config.h"
-#include "media/base/audio_bus.h"
-
-namespace audio_modem {
-
-void PopulateSamples(unsigned int random_seed, size_t size, float* samples) {
-// On Windows, rand() is threadsafe, and rand_r() is not available.
-#if defined(OS_WIN)
-  srand(random_seed);
-  for (size_t i = 0; i < size; ++i)
-    samples[i] = (2.0 * rand() / RAND_MAX) - 1;  // NOLINT
-#else
-  for (size_t i = 0; i < size; ++i)
-    samples[i] = (2.0 * rand_r(&random_seed) / RAND_MAX) - 1;
-#endif
-}
-
-scoped_refptr<media::AudioBusRefCounted>
-CreateRandomAudioRefCounted(int random_seed, int channels, int samples) {
-  scoped_refptr<media::AudioBusRefCounted> bus =
-      media::AudioBusRefCounted::Create(channels, samples);
-  for (int ch = 0; ch < channels; ++ch)
-    PopulateSamples(random_seed, samples, bus->channel(ch));
-  return bus;
-}
-
-}  // namespace audio_modem