First version of a QUIC SendAlgorithmSimulator which is designed to

net/quic/test_tools/quic_test_utils.h

Index: net/quic/test_tools/quic_test_utils.h
diff --git a/net/quic/test_tools/quic_test_utils.h b/net/quic/test_tools/quic_test_utils.h
index 4c6fcf1c1780771235910d9556ab0bc5bc2f6ae0..6d1de91cdf785d62e8d7ce49db99f995b6d3f8cd 100644
--- a/net/quic/test_tools/quic_test_utils.h
+++ b/net/quic/test_tools/quic_test_utils.h
@@ -122,6 +122,25 @@ class ValueRestore {
   DISALLOW_COPY_AND_ASSIGN(ValueRestore);
 };
 
+// Simple random number generator used to compute random numbers suitable
+// for pseudo-randomly dropping packets in tests.  It works by computing
+// the sha1 hash of the current seed, and using the first 64 bits as
+// the next random number, and the next seed.
+class SimpleRandom {
+ public:
+  SimpleRandom() : seed_(0) {}
+
+  // Returns a random number in the range [0, kuint64max].
+  uint64 RandUint64();
+
+  void set_seed(uint64 seed) { seed_ = seed; }
+
+ private:
+  uint64 seed_;
+
+  DISALLOW_COPY_AND_ASSIGN(SimpleRandom);
+};
+
 class MockFramerVisitor : public QuicFramerVisitorInterface {
  public:
   MockFramerVisitor();