Factoring GUID generation from metrics to base

base/rand_util_win.cc

 // Copyright (c) 2008 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/rand_util.h"
 
 #include <stdlib.h>
 
+#include <objbase.h>
+#include <windows.h>
+
 #include "base/basictypes.h"
 #include "base/logging.h"
+#include "base/string_util.h"
+#include "base/utf_string_conversions.h"
 
 namespace {
 
 uint32 RandUint32() {
   uint32 number;
   CHECK_EQ(rand_s(&number), 0);
   return number;
 }
 
 }  // namespace
 
 namespace base {
 
 uint64 RandUint64() {
   uint32 first_half = RandUint32();
   uint32 second_half = RandUint32();
   return (static_cast<uint64>(first_half) << 32) + second_half;
 }
 
+std::string GenerateGUID() {
+  const int kGUIDSize = 39;
+
+  GUID guid;
+  HRESULT guid_result = CoCreateGuid(&guid);
+  DCHECK(SUCCEEDED(guid_result));
+
+  std::wstring guid_string;
+  int result = StringFromGUID2(guid,
+                               WriteInto(&guid_string, kGUIDSize), kGUIDSize);
+  DCHECK(result == kGUIDSize);
+
+  return WideToUTF8(guid_string.substr(1, guid_string.length() - 2));
+}
+
 }  // namespace base