ES6 Style: add presubmit prompt about => in code that might run on iOS9

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 re
 import subprocess
 import unittest
 
 import PRESUBMIT
@@ skipping 394 matching lines @@
 
   def testSingletonInCC(self):
     diff_cc = ['Foo* foo = base::Singleton<Foo>::get();']
     mock_input_api = MockInputApi()
     mock_input_api.files = [MockAffectedFile('some/path/foo.cc', diff_cc)]
     warnings = PRESUBMIT._CheckSingletonInHeaders(mock_input_api,
                                                   MockOutputApi())
     self.assertEqual(0, len(warnings))
 
 
-class CheckNoDeprecatedCompiledResourcesGYPTest(unittest.TestCase):
-  def testNoDeprecatedCompiledResourcsGYP(self):
+class CheckNoDeprecatedCompiledResourcesGypTest(unittest.TestCase):
+  def testNoDeprecatedCompiledResourcsGyp(self):
     mock_input_api = MockInputApi()
     mock_input_api.files = [MockFile('some/js/compiled_resources.gyp', [])]
-    errors = PRESUBMIT._CheckNoDeprecatedCompiledResourcesGYP(mock_input_api,
+    errors = PRESUBMIT._CheckNoDeprecatedCompiledResourcesGyp(mock_input_api,
                                                               MockOutputApi())
     self.assertEquals(1, len(errors))
 
     mock_input_api.files = [MockFile('some/js/compiled_resources2.gyp', [])]
-    errors = PRESUBMIT._CheckNoDeprecatedCompiledResourcesGYP(mock_input_api,
+    errors = PRESUBMIT._CheckNoDeprecatedCompiledResourcesGyp(mock_input_api,
                                                               MockOutputApi())
     self.assertEquals(0, len(errors))
 
 
 class InvalidOSMacroNamesTest(unittest.TestCase):
   def testInvalidOSMacroNames(self):
     lines = ['#if defined(OS_WINDOWS)',
              ' #elif defined(OS_WINDOW)',
              ' # if defined(OS_MACOSX) || defined(OS_CHROME)',
              '# else  // defined(OS_MAC)',
@@ skipping 746 matching lines @@
       MockAffectedFile('third_party\\WebKit\\header.h', [
         'class DummyClass;',
         'struct DummyStruct;',
       ])
     ]
     warnings = PRESUBMIT._CheckUselessForwardDeclarations(mock_input_api,
       MockOutputApi())
     self.assertEqual(4, len(warnings))
 
 
+class RiskyJsTest(unittest.TestCase):
+  def testArrowWarnInIos9Code(self):
+    mock_input_api = MockInputApi()
+    mock_output_api = MockOutputApi()
+
+    mock_input_api.files = [
+      MockAffectedFile('components/blah.js', ["shouldn't use => here"]),
+    ]
+    warnings = PRESUBMIT._CheckForRiskyJsFeatures(
+        mock_input_api, mock_output_api)
+    self.assertEqual(1, len(warnings))
+
+    mock_input_api.files = [
+      MockAffectedFile('ios/blee.js', ['might => break folks']),
+    ]
+    warnings = PRESUBMIT._CheckForRiskyJsFeatures(
+        mock_input_api, mock_output_api)
+    self.assertEqual(1, len(warnings))
+
+    mock_input_api.files = [
+      MockAffectedFile('ui/webui/resources/blarg.js', ['on => iOS9']),
+    ]
+    warnings = PRESUBMIT._CheckForRiskyJsFeatures(
+        mock_input_api, mock_output_api)
+    self.assertEqual(1, len(warnings))
+
+  def testArrowsAllowedInChromeCode(self):
+    mock_input_api = MockInputApi()
+    mock_input_api.files = [
+      MockAffectedFile('chrome/browser/resources/blah.js', 'arrow => OK here'),
+    ]
+    warnings = PRESUBMIT._CheckForRiskyJsFeatures(
+        mock_input_api, MockOutputApi())
+    self.assertEqual(0, len(warnings))
+
+
 if __name__ == '__main__':
   unittest.main()