Add js_interface_generator for generating extensions interfaces

tools/json_schema_compiler/js_externs_generator_test.py

Index: tools/json_schema_compiler/js_externs_generator_test.py
diff --git a/tools/json_schema_compiler/js_externs_generator_test.py b/tools/json_schema_compiler/js_externs_generator_test.py
index cdf49301c7b7372a99a401d2212f6e22d3e39356..20a1d1a81237f8bce2295d92eb1711bf539e5e48 100755
--- a/tools/json_schema_compiler/js_externs_generator_test.py
+++ b/tools/json_schema_compiler/js_externs_generator_test.py
@@ -11,19 +11,6 @@ import model
 import sys
 import unittest
 
-COPYRIGHT = ("""// Copyright %s 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.
-""" % datetime.now().year)
-
-INFO = """// This file was generated by:
-//   %s.
-// 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.
-"""
-
 # The contents of a fake idl file.
 fake_idl = """
 // Copyright 2014 The Chromium Authors. All rights reserved.
@@ -85,8 +72,7 @@ namespace fakeApi {
 """
 
 # The output we expect from our fake idl file.
-expected_output = COPYRIGHT + "\n" + (INFO % (sys.argv[0], "fakeApi")) + """
-/** @fileoverview Externs generated from namespace: fakeApi */
+expected_output = JsExternsGenerator.GetHeader(sys.argv[0], 'fakeApi') + """

[Devlin, 2015/12/07 18:55:27]

I slightly prefer having this hard-coded, even if it's simplistic.  Just in the
spirit of testing literal expected output, vs relying on internal functions.

Also, if this allows us to make GetHeader non-static (this is the only other use
of it I saw?), that's an added win.

[stevenjb, 2015/12/07 19:49:32]

Sigh. The previous way isn't any better IMHO because we a) define INFO above and
b) pass multiple arguments to it.

I will go ahead and explicitly embed the entire expected header (passing just
year and tool name), although I feel it falls pretty firmly into the category of
testing something that doesn't really need testing, i.e. adding maintenance cost
(already kinda high) without much benefit.

 
 /**
  * @const
@@ -161,8 +147,7 @@ chrome.fakeApi.returnString = function() {};
  * @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.
@@ -235,8 +220,7 @@ fake_json = """// Copyright 2014 The Chromium Authors. All rights reserved.
   }
 ]"""
 
-json_expected = COPYRIGHT + "\n" + (INFO % (sys.argv[0], "fakeJson")) + """
-/** @fileoverview Externs generated from namespace: fakeJson */
+json_expected = JsExternsGenerator.GetHeader(sys.argv[0], 'fakeJson') + """
 
 /**
  * @const
@@ -272,8 +256,7 @@ chrome.fakeJson.CrazyEnum = {
  * }}
  * @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):