Remove 'using base::string16;' from base/strings/string16.h and remove temporary

PRESUBMIT.py

 # 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.
 
 """Top-level presubmit script for Chromium.
 
 See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
 for more details about the presubmit API built into gcl.
 """
 
@@ skipping 1019 matching lines @@
   results.extend(_CheckAddedDepsHaveTargetApprovals(input_api, output_api))
   results.extend(
       input_api.canned_checks.CheckChangeHasNoTabs(
           input_api,
           output_api,
           source_file_filter=lambda x: x.LocalPath().endswith('.grd')))
   results.extend(_CheckSpamLogging(input_api, output_api))
   results.extend(_CheckForAnonymousVariables(input_api, output_api))
   results.extend(_CheckCygwinShell(input_api, output_api))
   results.extend(_CheckJavaStyle(input_api, output_api))
-  results.extend(_CheckForString16(input_api, output_api))
 
   if any('PRESUBMIT.py' == f.LocalPath() for f in input_api.AffectedFiles()):
     results.extend(input_api.canned_checks.RunUnitTestsInDirectory(
         input_api, output_api,
         input_api.PresubmitLocalPath(),
         whitelist=[r'^PRESUBMIT_test\.py$']))
   return results
 
 
 def _CheckSubversionConfig(input_api, output_api):
@@ skipping 122 matching lines @@
       bad_macros.extend(_CheckForInvalidOSMacrosInFile(input_api, f))
 
   if not bad_macros:
     return []
 
   return [output_api.PresubmitError(
       'Possibly invalid OS macro[s] found. Please fix your code\n'
       'or add your macro to src/PRESUBMIT.py.', bad_macros)]
 
 
-def _CheckForString16InFile(input_api, f):
-  """Check for string16 without base:: in front."""
-  reg = input_api.re.compile(r'\b(?<!base::)string16\b')
-  use = 'using base::string16;'
-  include = '#include "base/strings/string16.h"'
-  results = []
-  for lnum, line in f.ChangedContents():
-    if reg.search(line) and not include in line and not use in f.NewContents():
-      results.append('    %s:%d' % (f.LocalPath(), lnum))
-  return results
-
-
-def _CheckForString16(input_api, output_api):
-  file_filter = lambda f: input_api.FilterSourceFile(f,
-      white_list=(
-          r'^android_webview[\\\/]',
-          r'^apps[\\\/]',
-          r'^ash[\\\/]',
-          r'^chrome[\\\/]',
-          r'^chrome_frame[\\\/]',
-          r'^chromeos[\\\/]',
-          r'^components[\\\/]',
-          r'^content[\\\/]',
-          r'^device[\\\/]',
-          r'^ipc[\\\/]',
-          r'^net[\\\/]',
-          r'^ppapi[\\\/]',
-          r'^printing[\\\/]',
-          r'^rlz[\\\/]',
-          r'^skia[\\\/]',
-          r'^tools[\\\/]',
-          r'^ui[\\\/]',
-          r'^webkit[\\\/]',
-          r'^win8[\\\/]',
-      ),
-      black_list=(_EXCLUDED_PATHS + _TEST_CODE_EXCLUDED_PATHS +
-                  input_api.DEFAULT_BLACK_LIST))
-
-  unprefixed = []
-  for f in input_api.AffectedFiles(file_filter=file_filter):
-    unprefixed.extend(_CheckForString16InFile(input_api, f))
-
-  if not unprefixed:
-    return []
-
-  return [output_api.PresubmitPromptWarning(
-      'string16 should be prefixed with base:: namespace.', unprefixed)]
-
-
 def CheckChangeOnUpload(input_api, output_api):
   results = []
   results.extend(_CommonChecks(input_api, output_api))
   return results
 
 
 def GetDefaultTryConfigs(bots=None):
   """Returns a list of ('bot', set(['tests']), optionally filtered by [bots].
 
   To add tests to this list, they MUST be in the the corresponding master's
@@ skipping 236 matching lines @@
     trybots.extend(GetDefaultTryConfigs(['cros_x86']))
 
   # The AOSP bot doesn't build the chrome/ layer, so ignore any changes to it
   # unless they're .gyp(i) files as changes to those files can break the gyp
   # step on that bot.
   if (not all(re.search('^chrome', f) for f in files) or
       any(re.search('\.gypi?$', f) for f in files)):
     trybots.extend(GetDefaultTryConfigs(['android_aosp']))
 
   return trybots