[Extension API Extern Generation] Fix comment indentation

tools/json_schema_compiler/js_externs_generator_test.py

 #!/usr/bin/env python
 # 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.
 
 import idl_schema
 from js_externs_generator import JsExternsGenerator
 from datetime import datetime
 import model
 import unittest
@@ skipping 36 matching lines @@
   callback VoidCallback = void();
 
   callback BazGreekCallback = void(Baz baz, Greek greek);
 
   interface Functions {
     // Does something exciting! And what's more, this is a multiline function
     // comment! It goes onto multiple lines!
     // |baz| : The baz to use.
     static void doSomething(Baz baz, VoidCallback callback);
 
+    // |callback| : The callback which will most assuredly in all cases be
+    // called; that is, of course, iff such a callback was provided and is
+    // not at all null.
     static void bazGreek(optional BazGreekCallback callback);
 
     [deprecated="Use a new method."] static DOMString returnString();
   };
 };
 """
 
 # The output we expect from our fake idl file.
 expected_output = """// Copyright %s The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
@@ skipping 43 matching lines @@
 
 /**
  * Does something exciting! And what's more, this is a multiline function
  * comment! It goes onto multiple lines!
  * @param {Baz} baz The baz to use.
  * @param {function():void} callback
  */
 chrome.fakeApi.doSomething = function(baz, callback) {};
 
 /**
- * @param {function(Baz, !chrome.fakeApi.Greek):void=} callback
+ * @param {function(Baz, !chrome.fakeApi.Greek):void=} callback The callback
+ *     which will most assuredly in all cases be called; that is, of course, iff
+ *     such a callback was provided and is not at all null.
  */
 chrome.fakeApi.bazGreek = function(callback) {};
 
 /**
  * @return {string}
  * @deprecated Use a new method.
  */
 chrome.fakeApi.returnString = function() {};
 """ % datetime.now().year
 
 
 class JsExternGeneratorTest(unittest.TestCase):
   def testBasic(self):
     self.maxDiff = None # Lets us see the full diff when inequal.
     filename = 'fake_api.idl'
     api_def = idl_schema.Process(fake_idl, filename)
     m = model.Model()
     namespace = m.AddNamespace(api_def[0], filename)
     self.assertMultiLineEqual(expected_output,
                               JsExternsGenerator().Generate(namespace).Render())
 
 
 if __name__ == '__main__':
   unittest.main()