Fix more disabled MSVC warnings, base/ edition.

base/metrics/field_trial_unittest.cc

 // Copyright (c) 2012 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/metrics/field_trial.h"
 
 #include "base/message_loop/message_loop.h"
 #include "base/rand_util.h"
 #include "base/run_loop.h"
 #include "base/strings/string_number_conversions.h"
@@ skipping 94 matching lines @@
   EXPECT_EQ(trial1.get(), FieldTrialList::Find(name1));
   EXPECT_EQ(trial2.get(), FieldTrialList::Find(name2));
   // Note: FieldTrialList should delete the objects at shutdown.
 }
 
 TEST_F(FieldTrialTest, AbsoluteProbabilities) {
   char always_true[] = " always true";
   char default_always_true[] = " default always true";
   char always_false[] = " always false";
   char default_always_false[] = " default always false";
-  for (int i = 1; i < 250; ++i) {
+  for (char i = 1; i < 250; ++i) {
     // Try lots of names, by changing the first character of the name.
     always_true[0] = i;
     default_always_true[0] = i;
     always_false[0] = i;
     default_always_false[0] = i;
 
     scoped_refptr<FieldTrial> trial_true =
         CreateFieldTrial(always_true, 10, default_always_true, NULL);
     const std::string winner = "TheWinner";
     int winner_group = trial_true->AppendGroup(winner, 10);
@@ skipping 56 matching lines @@
   } while ((!second_winner || !first_winner) && counter < 100);
   EXPECT_TRUE(second_winner);
   EXPECT_TRUE(first_winner);
 }
 
 TEST_F(FieldTrialTest, MiddleProbabilities) {
   char name[] = " same name";
   char default_group_name[] = " default same name";
   bool false_event_seen = false;
   bool true_event_seen = false;
-  for (int i = 1; i < 250; ++i) {
+  for (char i = 1; i < 250; ++i) {
     name[0] = i;
     default_group_name[0] = i;
     scoped_refptr<FieldTrial> trial =
         CreateFieldTrial(name, 10, default_group_name, NULL);
     int might_win = trial->AppendGroup("MightWin", 5);
 
     if (trial->group() == might_win) {
       true_event_seen = true;
     } else {
       false_event_seen = true;
@@ skipping 781 matching lines @@
     EXPECT_TRUE(active_groups.empty());
 
     // The trial shouldn't be listed in the |StatesToString()| result.
     std::string states;
     FieldTrialList::StatesToString(&states);
     EXPECT_TRUE(states.empty());
   }
 }
 
 }  // namespace base