Vulcanize MD History to improve page-load performance

chrome/browser/resources/md_history/PRESUBMIT.py

+# Copyright 2016 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.
+
+
+def CheckChangeOnUpload(input_api, output_api):
+  """Warn when changing md_history without vulcanizing."""
+
+  def _is_md_history_file(path):
+    return (path.startswith('chrome/browser/resources/md_history') and
+            (not path.endswith('externs.js')) and
+            (path.endswith('js') or path.endswith('html')))
+
+  def _affects_file(filename, paths):
+    return any([filename in path for path in paths])
+
+  paths = [x.LocalPath() for x in input_api.change.AffectedFiles()]
+  vulcanize_changes = (_affects_file('md_history/app.vulcanized.html', paths) or
+                       _affects_file('md_history/app.crisper.js', paths))
+  history_changes = filter(_is_md_history_file, paths)

[michaelpg, 2016/08/11 07:42:14]

IDK how useful this is; we ought to include changes to third_party/polymer and
ui/webui/resources as well, but it's hard to limit that to files inlined via
vulcanize/crisper. And Downloads should have a similar presubmit.

Ultimately I think "set noparent" in OWNERS is the only way to guard against
mistakes without node in the build toolchain.

[tsergeant, 2016/08/15 05:54:18]

I'm aware that this will have false negatives, and I'm okay with it.

This is mostly just to ensure that the vulcanized doesn't get too out of sync
while history is being actively developed. I don't think Downloads really needs
the same thing since changes are relatively infrequent.

+
+  if history_changes and not vulcanize_changes:
+    return [output_api.PresubmitPromptWarning(
+        'Vulcanize must be run when changing files in md_history. See '
+        'chrome/browser/resources/vulcanize.py.')]

[michaelpg, 2016/08/11 07:42:14]

maybe docs/vulcanize.md instead?

[tsergeant, 2016/08/15 05:54:18]

Done.

+  return []