Provide script/gypi support for manifest generation

chrome/browser/resources/chromeos/chromevox/generate_manifest.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.
+
+# Generates an output manifest based on a Jinja2 templated manifest.

[Peter Lundblad, 2014/05/23 16:04:27]

nit: s/an output/a/

[Peter Lundblad, 2014/05/23 16:04:27]

nit: mention that this is expected to be included inside a target.

[David Tseng, 2014/05/23 19:16:37]

Done.

[David Tseng, 2014/05/23 19:16:37]

I don't claim to be a grammar wiz, but greping for "a output" resulted in no
results while there was one other use of "an output" (in a gypi file).

+# The following variables must be set before including this file:
+#
+# template_manifest: a valid JSON file path.

[Peter Lundblad, 2014/05/23 16:04:27]

nit: it's a path to a jinja2 file.

[Peter Lundblad, 2014/05/23 16:04:27]

Usually file name variable end in -Ifle and _path so that relative paths are
handled correctly on merging.

[David Tseng, 2014/05/23 19:16:37]

Done.

+# output_manifest: file path with the resulting manifest.

[Peter Lundblad, 2014/05/23 16:04:27]

s/with/for?

[David Tseng, 2014/05/23 19:16:37]

Sure; why not.

+
+{
+  'actions': [
+    {
+      'action_name': 'generate_manifest',
+      'message': 'Generate manifest for <(_target_name)',
+      'variables': {
+        'is_guest_manifest%': 0,
+      },
+      'inputs': [
+        'tools/generate_manifest.py',
+        '<(template_manifest)',
+      ],
+      'outputs': [
+        '<(output_manifest)'
+      ],
+      'action': [
+        'python',
+        'tools/generate_manifest.py',
+        '-o', '<(output_manifest)',
+        '-g', '<(is_guest_manifest)',
+        '<(template_manifest)'
+      ],
+    },
+  ],
+}