IDL build: factor out global constructors action into a GYP template

Source/bindings/scripts/global_objects.gypi

 # 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.
 #
 # This file is meant to be included into a target to provide an action
 # to compute global objects in a component.
 #
 # To use this, create a gyp target with the following form:
 # {
 #   'target_name': 'component_global_objects',
 #   'variables': {
 #     'idl_files': '<(list_of_idl_files)',
 #     'input_files': ['<(some_dir)/GlobalObjectBaseComponent.pickle'],
 #     'output_file': '<(some_dir)/GlobalObjectsComponent.pickle',
 #   },
 #   'includes': ['path/to/this/gypi/file'],
 # },
 #
 # Required variables:
 #  idl_files - List of .idl files that will be searched in.
 #    This should *only* contain main IDL files, excluding dependencies and
-#    testing, which should not define global objects).
+#    testing, which should not define global objects.
 #  output_file - Pickle file of output.
 #
 # Optional variables:
 #  input_files - List of input pickle files of global objects in base
 #    components. In this case make sure to include a dependencies section
 #    in the target to ensure this is generated.
 #
 # Spec: http://heycam.github.io/webidl/#Global
 # Design document: http://www.chromium.org/developers/design-documents/idl-build
 
 {
   'type': 'none',
   'actions': [{
     'action_name': 'compute_<(_target_name)',
     'message': 'Computing global objects for <(_target_name)',
     'variables': {
       'input_files%': [],
-      'idl_files_list': '<|(idl_files_list.tmp <@(idl_files))',
+      'idl_files_list': '<|(<(_target_name)_idl_files_list.tmp <@(idl_files))',
     },
     'includes': ['scripts.gypi'],
     'inputs': [
       '<(bindings_scripts_dir)/compute_global_objects.py',
       '<(bindings_scripts_dir)/utilities.py',
       '<(idl_files_list)',
       '<@(idl_files)',
     ],
     'outputs': [
       '<(output_file)',
     ],
     'action': [
       'python',
       '<(bindings_scripts_dir)/compute_global_objects.py',
       '--idl-files-list',
       '<(idl_files_list)',
       '--write-file-only-if-changed',
       '<(write_file_only_if_changed)',
       '--',
       '<@(input_files)',
       '<(output_file)',
      ],
   }],
 }