IDL generated extensions code only generate foo_api.h when required

tools/json_schema_compiler/compiler.py

 #!/usr/bin/env python
 # 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.
 """Generator for C++ structs from api json files.
 
 The purpose of this tool is to remove the need for hand-written code that
 converts to and from base::Value types when receiving javascript api calls.
 Originally written for generating code for extension apis. Reference schemas
 are in chrome/common/extensions/api.
@@ skipping 135 matching lines @@
       sys.exit("Filename %s is illegal. Name files using unix_hacker style." %
                schema_filename)
 
   type_generator = cpp_type_generator.CppTypeGenerator(root_namespace)
   for referenced_namespace in api_model.namespaces.values():
     type_generator.AddNamespace(
         referenced_namespace,
         referenced_namespace.unix_name)
 
   generator = schema_bundle_generator.SchemaBundleGenerator(
-      api_model, api_defs, type_generator)
+      root, api_model, api_defs, type_generator)
   api_h_code = generator.GenerateAPIHeader().Render()
   schemas_h_code = generator.GenerateSchemasHeader().Render()
   schemas_cc_code = generator.GenerateSchemasCC().Render()
 
   if dest_dir:
     basedir = os.path.join(dest_dir, 'chrome/common/extensions/api')
     with open(os.path.join(basedir, 'generated_api.h'), 'w') as h_file:
       h_file.write(api_h_code)
     with open(os.path.join(basedir, 'generated_schemas.h'), 'w') as h_file:
       h_file.write(schemas_h_code)
@@ skipping 31 matching lines @@
 
   if not args:
     sys.exit(0) # This is OK as a no-op
   dest_dir = opts.destdir
   root_namespace = opts.namespace
 
   if opts.bundle:
     handle_bundle_schema(args, dest_dir, opts.root, root_namespace)
   else:
     handle_single_schema(args[0], dest_dir, opts.root, root_namespace)