Factoring GUID generation from metrics to base

base/rand_util.h

Index: base/rand_util.h
diff --git a/base/rand_util.h b/base/rand_util.h
index 699fc7fabbec89065ad3a4afe0146c524b050b0f..d2981344d22cda987ffc23a3974243d4489bfbd0 100644
--- a/base/rand_util.h
+++ b/base/rand_util.h
@@ -6,6 +6,8 @@
 #define BASE_RAND_UTIL_H_
 #pragma once
 
+#include <string>
+
 #include "base/basictypes.h"
 
 namespace base {
@@ -26,6 +28,9 @@ uint64 RandGenerator(uint64 max);
 // Returns a random double in range [0, 1). Thread-safe.
 double RandDouble();
 
+// Generate a 128-bit random GUID of the form: "%08X-%04X-%04X-%04X-%012llX".
+std::string GenerateGUID();
+
 }  // namespace base
 
 #endif  // BASE_RAND_UTIL_H_