Implement declarativeContent API.

chrome/test/data/extensions/api_test/declarative_content/overview/background.js

+// Copyright (c) 2012 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.
+
+var declarative = chrome.declarative;
+
+var PageStateMatcher = chrome.declarativeContent.PageStateMatcher;
+var ShowPageAction = chrome.declarativeContent.ShowPageAction;
+
+var rule0 = {
+  conditions: [new PageStateMatcher({pageUrl: {hostPrefix: "test1"}}),
+               new PageStateMatcher({css: ["input[type='password']"]})],
+  actions: [new ShowPageAction()]
+}
+
+var testEvent = chrome.declarativeContent.onPageChanged;
+
+testEvent.removeRules(undefined, function() {
+  testEvent.addRules([rule0], function() {
+    chrome.test.sendMessage("ready", function(reply) {
+    })
+  });
+});