chromium/chrome/test/data/extensions/subscribe_page_action_v2/src/doc_start.js

// Copyright 2010 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

debugMsg(logLevels.info, "Running script at document_start");

// See if the current document is a feed document and if so, let
// the extension know that we should show the subscribe page instead.
if (containsFeed(document))
  chrome.extension.sendMessage({msg: "feedDocument", href: location.href});