Add the QuicRandom interface with a default implementation that is

net/quic/crypto/quic_random.h

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef NET_QUIC_CRYPTO_QUIC_RANDOM_H_
+#define NET_QUIC_CRYPTO_QUIC_RANDOM_H_
+
+#include <stddef.h>
+
+#include "base/basictypes.h"
+
+namespace net {
+
+// The interface for a random number generator.
+class QuicRandom {
+ public:
+  virtual ~QuicRandom() {}
+
+  // Returns the default random number generator, which is cryptographically
+  // secure and thread-safe.
+  static QuicRandom* GetInstance();
+
+  // Generates |len| random bytes in the |data| buffer.
+  virtual void RandBytes(void* data, size_t len) = 0;
+
+  // Returns a random number in the range [0, kuint64max].
+  virtual uint64 RandUint64() = 0;
+
+  // Reseeds the random number generator with additional entropy input.
+  // NOTE: the constructor of a QuicRandom object is responsible for seeding
+  // itself with enough entropy input.
+  virtual void Reseed(const void* additional_entropy, size_t entropy_len) = 0;
+};
+
+}  // namespace net
+
+#endif  // NET_QUIC_CRYPTO_QUIC_RANDOM_H_