Adds PRESUBMIT.py check to look for unprefixed string16.

PRESUBMIT_test.py

 #!/usr/bin/env python
 # 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.
 
 import os
 import re
 import unittest
 
 import PRESUBMIT
@@ skipping 375 matching lines @@
     self.assertTrue(':1 OS_WINDOWS' in errors[0])
     self.assertTrue('(did you mean OS_WIN?)' in errors[0])
 
   def testValidOSMacroNames(self):
     lines = ['#if defined(%s)' % m for m in PRESUBMIT._VALID_OS_MACROS]
     errors = PRESUBMIT._CheckForInvalidOSMacrosInFile(
         MockInputApi(), MockFile('some/path/foo_platform.cc', lines))
     self.assertEqual(0, len(errors))
 
 
+class String16Test(unittest.TestCase):
+  def testUnprefixedGivesWarnings(self):
+    lines = ['string16 GetName() const;',
+             'void SetName(const string16& name) OVERRIDE {}',
+             'const string16& GetNameRef() const = 0;',
+             'string16 name;',
+             'string16 foo = ASCIIToUTF16("bar");',
+             'string16 blah(ASCIIToUTF16("blee"));',
+             'std::vector<string16> names;',
+             'string16 var_with_string16_in_name;']
+    warnings = PRESUBMIT._CheckForString16InFile(
+        MockInputApi(), MockFile('chrome/browser/name_getter_bad.cc', lines))
+    self.assertEqual(len(lines), len(warnings))
+
+  def testPrefixedSkipped(self):
+    lines = ['#include "base/strings/string16.h"',
+             'void SetName(const base::string16& name) OVERRIDE {}',
+             'const base::string16& GetNameRef() const = 0;',
+             'base::string16 name;',
+             'base::string16 foo = ASCIIToUTF16("bar");',
+             'base::string16 blah(ASCIIToUTF16("blee"));',
+             'std::vector<base::string16> names;',
+             'base::string16 var_with_string16_in_name;']
+    warnings = PRESUBMIT._CheckForString16InFile(
+        MockInputApi(), MockFile('chrome/browser/name_getter_good.cc', lines))
+    self.assertEqual(0, len(warnings))
+
+  def testUsingYieldsNoWarnings(self):
+    lines = ['#include "base/strings/string16.h',
+             'namespace {',
+             'using base::string16;',
+             'string16 SayHiOnlyToEd(const string16& name) {',
+             '  string16 first = name.substr(0, 2);  // Only "Ed" gets a "Hi".',
+             '  return first == "Ed" ? first : string16();',
+             '}']
+    warnings = PRESUBMIT._CheckForString16InFile(
+        MockInputApi(), MockFile('chrome/browser/say_hi_to_ed.cc', lines))
+    self.assertEqual(0, len(warnings))
+
+
 class CheckAddedDepsHaveTetsApprovalsTest(unittest.TestCase):
   def testDepsFilesToCheck(self):
     changed_lines = [
       '"+breakpad",',
       '"+chrome/installer",',
       '"+chrome/plugin/chrome_content_plugin_client.h",',
       '"+chrome/utility/chrome_content_utility_client.h",',
       '"+chromeos/chromeos_paths.h",',
       '"+components/breakpad",',
       '"+components/nacl/common",',
@@ skipping 19 matching lines @@
       'policy/DEPS',
       'sandbox/DEPS',
       'tools/memory_watcher/DEPS',
       'third_party/lss/DEPS',
     ])
     self.assertEqual(expected, files_to_check);
 
 
 if __name__ == '__main__':
   unittest.main()