update obsolete code.google.com documentation links

tools/json_schema_compiler/js_externs_generator.py

 # Copyright 2015 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.
 """
 Generator that produces an externs file for the Closure Compiler.
 Note: This is a work in progress, and generated externs may require tweaking.
 
 See https://developers.google.com/closure/compiler/docs/api-tutorial3#externs
 """
 
 from code import Code
 from js_util import JsUtil
 from model import *
 from schema_util import *
 
 import os
 import sys
 import re
 
 NOTE = """// NOTE: The format of types has changed. 'FooType' is now
 //   'chrome.%s.FooType'.
 // Please run the closure compiler before committing changes.
-// See https://code.google.com/p/chromium/wiki/ClosureCompilation.
+// See https://chromium.googlesource.com/chromium/src/+/master/docs/closure_compilation.md
 """
 
 class JsExternsGenerator(object):
   def Generate(self, namespace):
     return _Generator(namespace).Generate()
 
 class _Generator(object):
   def __init__(self, namespace):
     self._namespace = namespace
     self._js_util = JsUtil()
@@ skipping 152 matching lines @@
     c.Append('chrome.%s = {};' % self._namespace.name)
     c.Append()
 
   def _GetFunctionParams(self, function):
     """Returns the function params string for function.
     """
     params = function.params[:]
     if function.callback:
       params.append(function.callback)
     return ', '.join(param.name for param in params)