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

Source/bindings/scripts/global_constructors.gypi

Index: Source/bindings/scripts/global_constructors.gypi
diff --git a/Source/bindings/scripts/global_constructors.gypi b/Source/bindings/scripts/global_constructors.gypi
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+++ b/Source/bindings/scripts/global_constructors.gypi
@@ -0,0 +1,73 @@
+# 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': 'core_global_constructors_idls',
+#   'dependencies': [
+#     'component_global_objects',
+#   ],
+#   'variables': {
+#     'idl_files': '<(list_of_idl_files)',
+#     'global_objects_file': '<(some_dir)/GlobalObjectsComponent.pickle',
+#     'global_names_idl_files': [
+#       'GlobalName',
+#       '<(blink_core_output_dir)/GlobalScopeComponentConstructors.idl',
+#       # ...
+#     ],
+#     'outputs': [
+#       '<@(component_global_constructors_generated_idl_files)',
+#       '<@(component_global_constructors_generated_header_files)',
+#     ],
+#   },
+#   '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 appear on global objects.
+#  global_objects - Pickle file of global objects.
+#  global_names_idl_files - pairs (GlobalName, Constructors.idl)
+#  outputs - List of output files.
+#    Passed as a variable here, included by the template in the action.
+#
+# Spec: http://heycam.github.io/webidl/#Global
+#       http://heycam.github.io/webidl/#Exposed
+# Design document: http://www.chromium.org/developers/design-documents/idl-build
+
+{
+  'type': 'none',
+  'actions': [{
+    'action_name': 'generate_<(_target_name)',
+    'message': 'Generating IDL files for constructors on global objects for <(_target_name)',
+    'variables': {
+      'idl_files_list': '<|(<(_target_name)_idl_files_list.tmp <@(idl_files))',
+    },
+    'includes': ['scripts.gypi'],
+    'inputs': [
+      '<(bindings_scripts_dir)/generate_global_constructors.py',
+      '<(bindings_scripts_dir)/utilities.py',
+      '<(idl_files_list)',
+      '<@(idl_files)',
+      '<(global_objects_file)',
+    ],
+    'outputs': ['<@(outputs)'],
+    'action': [
+      'python',
+      '<(bindings_scripts_dir)/generate_global_constructors.py',
+      '--idl-files-list',
+      '<(idl_files_list)',
+      '--global-objects-file',
+      '<(global_objects_file)',
+      '--write-file-only-if-changed',
+      '<(write_file_only_if_changed)',
+      '--',
+      '<@(global_names_idl_files)',
+    ],
+  }],
+}