Send data from mixer to APM limiter more often.

webrtc/modules/audio_mixer/sine_wave_generator.h

+/*
+ *  Copyright (c) 2017 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef WEBRTC_MODULES_AUDIO_MIXER_SINE_WAVE_GENERATOR_H_
+#define WEBRTC_MODULES_AUDIO_MIXER_SINE_WAVE_GENERATOR_H_
+
+#include "webrtc/base/checks.h"
+#include "webrtc/modules/include/module_common_types.h"
+
+namespace webrtc {
+
+class SineWaveGenerator {
+ public:
+  SineWaveGenerator(float wave_frequency_hz, int16_t amplitude)
+      : wave_frequency_hz_(wave_frequency_hz), amplitude_(amplitude) {
+    RTC_DCHECK_GT(wave_frequency_hz, 0);
+  }
+
+  // Produces appropriate output based on frame->num_channels_,
+  // frame->sample_rate_hz_.
+  void GenerateNextFrame(AudioFrame* frame);
+
+ private:
+  float phase_ = 0.f;
+  const float wave_frequency_hz_;
+  const int16_t amplitude_;
+};
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_MODULES_AUDIO_MIXER_SINE_WAVE_GENERATOR_H_