Add RandomNumberGenerator adapter to base/rand_util.h

base/rand_util_unittest.cc

Index: base/rand_util_unittest.cc
diff --git a/base/rand_util_unittest.cc b/base/rand_util_unittest.cc
index f56c0ece09421ae098bc8ddca7b81138217714ae..cbc338a3b4eec23299af3c4a7d97082ed60904d0 100644
--- a/base/rand_util_unittest.cc
+++ b/base/rand_util_unittest.cc
@@ -27,3 +27,11 @@ TEST(RandUtilTest, RandDouble) {
  EXPECT_GT(1.0, number);
  EXPECT_LE(0.0, number);
 }
+
+// Make sure that it is still appropriate to use RandGenerator in conjunction
+// with std::random_shuffle().
+TEST(RandUtilTest, RandGeneratorForRandomShuffle) {
+  EXPECT_EQ(base::RandGenerator(1), 0U);
+  EXPECT_LE(std::numeric_limits<ptrdiff_t>::max(),
+            std::numeric_limits<int64>::max());
+}