Improve base::RandBytes() performance by 1.75x-2.10x on POSIX.

base/rand_util.cc

Index: base/rand_util.cc
diff --git a/base/rand_util.cc b/base/rand_util.cc
index 9641ff4f9c7c4ffe87aa5c7af7f9918d498799c4..1525b91449d438089a67b89f23521941a80e4500 100644
--- a/base/rand_util.cc
+++ b/base/rand_util.cc
@@ -61,16 +61,6 @@ uint64 RandGenerator(uint64 range) {
   return value % range;
 }
 
-void RandBytes(void* output, size_t output_length) {
-  uint64 random_int;
-  size_t random_int_size = sizeof(random_int);
-  for (size_t i = 0; i < output_length; i += random_int_size) {
-    random_int = base::RandUint64();
-    size_t copy_count = std::min(output_length - i, random_int_size);
-    memcpy(((uint8*)output) + i, &random_int, copy_count);
-  }
-}
-
 std::string RandBytesAsString(size_t length) {
   DCHECK_GT(length, 0u);
   std::string result;