Move PRNG from BWE test framework to webrtc/test.

webrtc/test/random.h

 /*
  *  Copyright (c) 2015 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_REMOTE_BITRATE_ESTIMATOR_TEST_RANDOM_H_
-#define WEBRTC_MODULES_REMOTE_BITRATE_ESTIMATOR_TEST_RANDOM_H_
+#ifndef WEBRTC_TEST_RANDOM_H_
+#define WEBRTC_TEST_RANDOM_H_
 
 #include "webrtc/typedefs.h"
 #include "webrtc/base/constructormagic.h"
 
 namespace webrtc {
 
+namespace test {
+
 class Random {
  public:
   explicit Random(uint32_t seed);
 
   // Return pseudo-random number in the interval [0.0, 1.0].

[pbos-webrtc, 2015/10/15 10:28:02]

Is this 1.0 inclusive?

[the sun, 2015/10/16 21:50:31]

Yes, that is why it says so. :)
https://en.wikipedia.org/wiki/Interval_(mathematics)

[pbos-webrtc, 2015/10/19 13:33:01]

I thought [0.0, 1.0) was the "standard" one, since that's what Python does.

[the sun, 2015/10/19 15:10:25]

Acknowledged.

   float Rand();
 
+  // Return pseudo rounded random number in interval [low, high].
+  int Rand(int low, int high);

[pbos-webrtc, 2015/10/15 10:28:02]

pseudo-random number mapped to the interval

+
   // Normal Distribution.
   int Gaussian(int mean, int standard_deviation);
 
+  // Exponential Distribution.
+  int Exponential(float lambda);
+
   // TODO(solenberg): Random from histogram.
   // template<typename T> int Distribution(const std::vector<T> histogram) {
 
  private:
   uint32_t a_;
   uint32_t b_;
 
   RTC_DISALLOW_IMPLICIT_CONSTRUCTORS(Random);
 };
+}  // namespace test
 }  // namespace webrtc
 
-#endif  // WEBRTC_MODULES_REMOTE_BITRATE_ESTIMATOR_TEST_RANDOM_H_
+#endif  // WEBRTC_TEST_RANDOM_H_