Added crypto random-number generator

base/rand_util.h

Index: base/rand_util.h
diff --git a/base/rand_util.h b/base/rand_util.h
index c5c4ef88114427a8ddf8ddebdd9499422e2f14fe..4b5b2d895423bf4b252fb850571b5ce724af4a69 100644
--- a/base/rand_util.h
+++ b/base/rand_util.h
@@ -32,12 +32,19 @@ BASE_EXPORT double RandDouble();
 // the range [0, 1). Thread-safe.
 BASE_EXPORT double BitsToOpenEndedUnitInterval(uint64 bits);
 
-// Fills |output_length| bytes of |output| with cryptographically strong random
-// data.
+// Fills |output_length| bytes of |output| with random data.
+//
+// WARNING:
+// Do not use for security-sensitive purposes.
+// See crypto/ for cryptographically secure random number generation APIs.
 BASE_EXPORT void RandBytes(void* output, size_t output_length);
 
-// Fills a string of length |length| with with cryptographically strong random
-// data and returns it.  |length| should be nonzero.
+// Fills a string of length |length| with with random data and returns it.
+// |length| should be nonzero.
+//
+// WARNING:
+// Do not use for security-sensitive purposes.
+// See crypto/ for cryptographically secure random number generation APIs.
 //
 // Note that this is a variation of |RandBytes| with a different return type.

[darin (slow to review), 2012/08/02 18:07:09]

micro-nit: I would put this note above the warning so that the warning is in the
same place for each function.

 BASE_EXPORT std::string RandBytesAsString(size_t length);