[ObjC ARC] Converts ios/chrome/common:unit_tests to ARC.

ios/chrome/common/ns_regular_expression_unittest.mm

 // Copyright 2013 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/strings/sys_string_conversions.h"
 #import "testing/gtest_mac.h"
 #include "testing/platform_test.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 // Chromium code relies on NSRegularExpression class to match regular
 // expressions.  Any subtle changes in behavior can lead to hard to diagnose
 // problems.  This files tests how NSRegularExpression handles various regular
 // expression features.
 
 namespace {
 
 // Checks that capture groups from |testString| substituted into
 // |templateString| matches |expected|.
 void ExpectRegexMatched(NSRegularExpression* regex,
@@ skipping 105 matching lines @@
   regex = MakeRegularExpression(@"^ab|cd|efghij$");
   ExpectRegexMatched(regex, @"ab", @"$0", @"ab");
   ExpectRegexMatched(regex, @"cd", @"$0", @"cd");
   ExpectRegexMatched(regex, @"efghij", @"$0", @"efghij");
   ExpectRegexNotMatched(regex, @"abcdefghij");
   ExpectRegexNotMatched(regex, @"abghij");
   ExpectRegexNotMatched(regex, @"cdghij");
 }
 
 }  // namespace