Update audio_processing module

Corresponds to upstream commit 524e9b043e7e86fd72353b987c9d5f6a1ebf83e1

Update notes:

 * Pull in third party license file

 * Replace .gypi files with BUILD.gn to keep track of what changes
   upstream

 * Bunch of new filse pulled in as dependencies

 * Won't build yet due to changes needed on top of these

webrtc/modules/audio_processing/transient/moving_moments.h

@@ -0,0 +1,52 @@
+/*
+ *  Copyright (c) 2013 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_PROCESSING_TRANSIENT_MOVING_MOMENTS_H_
+#define WEBRTC_MODULES_AUDIO_PROCESSING_TRANSIENT_MOVING_MOMENTS_H_
+
+#include <queue>
+
+#include "webrtc/base/scoped_ptr.h"
+
+namespace webrtc {
+
+// Calculates the first and second moments for each value of a buffer taking
+// into account a given number of previous values.
+// It preserves its state, so it can be multiple-called.
+// TODO(chadan): Implement a function that takes a buffer of first moments and a
+// buffer of second moments; and calculates the variances. When needed.
+// TODO(chadan): Add functionality to update with a buffer but only output are
+// the last values of the moments. When needed.
+class MovingMoments {
+ public:
+  // Creates a Moving Moments object, that uses the last |length| values
+  // (including the new value introduced in every new calculation).
+  explicit MovingMoments(size_t length);
+  ~MovingMoments();
+
+  // Calculates the new values using |in|. Results will be in the out buffers.
+  // |first| and |second| must be allocated with at least |in_length|.
+  void CalculateMoments(const float* in, size_t in_length,
+                        float* first, float* second);
+
+ private:
+  size_t length_;
+  // A queue holding the |length_| latest input values.
+  std::queue<float> queue_;
+  // Sum of the values of the queue.
+  float sum_;
+  // Sum of the squares of the values of the queue.
+  float sum_of_squares_;
+};
+
+}  // namespace webrtc
+
+
+#endif  // WEBRTC_MODULES_AUDIO_PROCESSING_TRANSIENT_MOVING_MOMENTS_H_