Move PRNG from BWE test framework to webrtc/test.

webrtc/modules/remote_bitrate_estimator/test/bwe_test_framework.cc

Index: webrtc/modules/remote_bitrate_estimator/test/bwe_test_framework.cc
diff --git a/webrtc/modules/remote_bitrate_estimator/test/bwe_test_framework.cc b/webrtc/modules/remote_bitrate_estimator/test/bwe_test_framework.cc
index d4201933e78e6d6ad25cafb85e4004e586893e0d..4574d3d8a1883c5d6aec2c742128469bf9128c0b 100644
--- a/webrtc/modules/remote_bitrate_estimator/test/bwe_test_framework.cc
+++ b/webrtc/modules/remote_bitrate_estimator/test/bwe_test_framework.cc
@@ -92,41 +92,6 @@ double RateCounter::BitrateWindowS() const {
   return static_cast<double>(window_size_us_) / (1000 * 1000);
 }
 
-Random::Random(uint32_t seed) : a_(0x531FDB97 ^ seed), b_(0x6420ECA8 + seed) {
-}
-
-float Random::Rand() {
-  const float kScale = 1.0f / 0xffffffff;
-  float result = kScale * b_;
-  a_ ^= b_;
-  b_ += a_;
-  return result;
-}
-
-int Random::Rand(int low, int high) {
-  float uniform = Rand() * (high - low + 1) + low;
-  return static_cast<int>(uniform);
-}
-
-int Random::Gaussian(int mean, int standard_deviation) {
-  // Creating a Normal distribution variable from two independent uniform
-  // variables based on the Box-Muller transform, which is defined on the
-  // interval (0, 1], hence the mask+add below.
-  const double kPi = 3.14159265358979323846;
-  const double kScale = 1.0 / 0x80000000ul;
-  double u1 = kScale * ((a_ & 0x7ffffffful) + 1);
-  double u2 = kScale * ((b_ & 0x7ffffffful) + 1);
-  a_ ^= b_;
-  b_ += a_;
-  return static_cast<int>(
-      mean + standard_deviation * sqrt(-2 * log(u1)) * cos(2 * kPi * u2));
-}
-
-int Random::Exponential(float lambda) {
-  float uniform = Rand();
-  return static_cast<int>(-log(uniform) / lambda);
-}
-
 Packet::Packet()
     : flow_id_(0),
       creation_time_us_(-1),
@@ -426,7 +391,7 @@ void JitterFilter::SetMaxJitter(int64_t max_jitter_ms) {
 }
 
 namespace {
-inline int64_t TruncatedNSigmaGaussian(Random* const random,
+inline int64_t TruncatedNSigmaGaussian(test::Random* const random,
                                        int64_t mean,
                                        int64_t std_dev) {
   int64_t gaussian_random = random->Gaussian(mean, std_dev);