Add js_interface_generator for generating extensions interfaces

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
 import json_parse
 from js_externs_generator import JsExternsGenerator
 from datetime import datetime
 import model
@@ skipping 143 matching lines @@
  * @deprecated Use a new method.
  * @see https://developer.chrome.com/extensions/fakeApi#method-returnString
  */
 chrome.fakeApi.returnString = function() {};
 
 /**
  * Fired when we realize it's a trap!
  * @type {!ChromeEvent}
  * @see https://developer.chrome.com/extensions/fakeApi#event-onTrapDetected
  */
-chrome.fakeApi.onTrapDetected;
-"""
+chrome.fakeApi.onTrapDetected;"""
 
 
 fake_json = """// Copyright 2014 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.
 
 [
   {
     "namespace": "fakeJson",
     "description": "Fake JSON API Stuff",
@@ skipping 89 matching lines @@
  *     description that causes problems!
  * @param {function({
  *   str: string
  * }):void} callback The callback to this heinous method
  * @return {{
  *   str: string,
  *   int: number
  * }}
  * @see https://developer.chrome.com/extensions/fakeJson#method-funcWithInlineObj
  */
-chrome.fakeJson.funcWithInlineObj = function(inlineObj, callback) {};
-"""
+chrome.fakeJson.funcWithInlineObj = function(inlineObj, callback) {};"""
 
 
 class JsExternGeneratorTest(unittest.TestCase):
   def _GetNamespace(self, fake_content, filename, is_idl):
     """Returns a namespace object for the given content"""
     api_def = (idl_schema.Process(fake_content, filename) if is_idl
         else json_parse.Parse(fake_content))
     m = model.Model()
     return m.AddNamespace(api_def[0], filename)
 
   def setUp(self):
     self.maxDiff = None # Lets us see the full diff when inequal.
 
   def testBasic(self):
     namespace = self._GetNamespace(fake_idl, 'fake_api.idl', True)
     self.assertMultiLineEqual(expected_output,
                               JsExternsGenerator().Generate(namespace).Render())
 
   def testJsonWithInlineObjects(self):
     namespace = self._GetNamespace(fake_json, 'fake_api.json', False)
     self.assertMultiLineEqual(json_expected,
                               JsExternsGenerator().Generate(namespace).Render())
 
 
 if __name__ == '__main__':
   unittest.main()