Switch to standard integer types in components/, part 4 of 4.

components/variations/active_field_trials_unittest.cc

 // Copyright 2014 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 "components/variations/active_field_trials.h"
 
+#include <stddef.h>
+
 #include "components/variations/metrics_util.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace variations {
 
 TEST(ActiveFieldTrialsTest, GetFieldTrialActiveGroups) {
   typedef std::set<ActiveGroupId, ActiveGroupIdCompare> ActiveGroupIdSet;
   std::string trial_one("trial one");
   std::string group_one("group one");
   std::string trial_two("trial two");
@@ skipping 25 matching lines @@
   for (size_t i = 0; i < active_group_ids.size(); ++i) {
     ActiveGroupIdSet::iterator expected_group =
         expected_groups.find(active_group_ids[i]);
     EXPECT_FALSE(expected_group == expected_groups.end());
     expected_groups.erase(expected_group);
   }
   EXPECT_EQ(0U, expected_groups.size());
 }
 
 }  // namespace variations