Upstream web js bundle.

ios/web/js_compile_bundle.gypi

+# 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.
+
+# This file is meant to be included into a target to provide a rule
+# to build JavaScript bundles using closure compiler.
+#
+# To use this, create a gyp target with the following form:
+# {
+#   'target_name': 'my_js_target',
+#   'type': 'none',
+#   'variables': {
+#     'closure_entry_point': 'name of the closure module',
+#     'js_bundle_files': ['path/to/dependency/file',],
+#   },
+#   'includes': ['path/to/this/gypi/file'],
+# }
+#
+# Required variables:
+#  closure_entry_point - name of the entry point closure module.
+#  js_bundle_files - list of js files to build a bundle.
+
+{
+  'variables': {
+    'closure_compiler_path': '<(DEPTH)/third_party/closure_compiler/compiler/compiler.jar',
+  },
+  'rules': [
+    {
+      'rule_name': 'jsbundlecompilation',
+      'extension': 'js',
+      'inputs': [
+        '<(closure_compiler_path)',
+        '<@(js_bundle_files)',
+      ],
+      'outputs': [
+        '<(SHARED_INTERMEDIATE_DIR)/<(RULE_INPUT_NAME)',
+      ],
+      'action': [
+        'java',
+        '-jar',
+        '<(closure_compiler_path)',
+        '--compilation_level',
+        'SIMPLE_OPTIMIZATIONS',
+        # Pass every js file to closure compiler. --only_closure_dependencies
+        # flag ensures that unnecessary files will not be compiled into the
+        # final output file.
+        '--js',
+        '<@(js_bundle_files)',
+        '--js_output_file',
+        '<@(_outputs)',
+        '--only_closure_dependencies',
+        '--closure_entry_point=<(closure_entry_point)',
+      ],
+      'message': 'Building <(RULE_INPUT_NAME) JavaScript bundle',
+    }  # rule_name: jsbundlecompilation
+  ]
+}