Add missing overflow handling to base::RandInt().

base/rand_util.cc

Index: base/rand_util.cc
diff --git a/base/rand_util.cc b/base/rand_util.cc
index 931eb4e943e646e2f39e2848b33683247b5b4725..655ff5bbde6fb51aba66472bab55e78bf04dd20a 100644
--- a/base/rand_util.cc
+++ b/base/rand_util.cc
@@ -20,7 +20,10 @@ int RandInt(int min, int max) {
   DCHECK_LE(min, max);
 
   uint64 range = static_cast<uint64>(max) - min + 1;
-  int result = min + static_cast<int>(base::RandGenerator(range));
+  // |range| is at most UINT_MAX + 1, so the result of RandGenerator(range)
+  // is at most UINT_MAX.  Hence it's safe to cast it from uint64 to int64.
+  int result =
+      static_cast<int>(min + static_cast<int64>(base::RandGenerator(range)));

[Lei Zhang, 2015/10/29 16:38:15]

int64_t, and fix line 22 as well?

[Nico, 2015/10/29 16:46:45]

Done.

   DCHECK_GE(result, min);
   DCHECK_LE(result, max);
   return result;