Injectable output rate calculater for AudioMixer.

webrtc/modules/audio_mixer/default_output_rate_calculator.h

Index: webrtc/modules/audio_mixer/default_output_rate_calculator.h
diff --git a/webrtc/modules/audio_mixer/default_output_rate_calculator.h b/webrtc/modules/audio_mixer/default_output_rate_calculator.h
new file mode 100644
index 0000000000000000000000000000000000000000..02c724dc6b1cc1ef90ede1eb8a9cd9680ab0e620
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+++ b/webrtc/modules/audio_mixer/default_output_rate_calculator.h
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+/*
+ *  Copyright (c) 2016 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_DEFAULT_OUTPUT_RATE_CALCULATOR_H_
+#define WEBRTC_MODULES_AUDIO_MIXER_DEFAULT_OUTPUT_RATE_CALCULATOR_H_
+
+#include <vector>
+
+#include "webrtc/modules/audio_mixer/output_rate_calculator.h"
+
+namespace webrtc {
+
+class DefaultOutputRateCalculator : public OutputRateCalculator {
+ public:
+  static const int kDefaultFrequency = 48000;
+
+  // Produces the least native rate greater or equal to the preferred
+  // sample rates. A native rate is one in
+  // AudioProcessing::NativeRate. If |preferred_sample_rates| is
+  // empty, returns |kDefaultFrequency|.
+  int CalculateOutputRate(
+      const std::vector<int>& preferred_sample_rates) override;
+  ~DefaultOutputRateCalculator() override {}
+};
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_MODULES_AUDIO_MIXER_DEFAULT_OUTPUT_RATE_CALCULATOR_H_