Allow extension APIs to be called from WebUI.

chrome/test/data/extensions/webui/sanity_check_available_apis.js

+// 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.
+
+// out/Debug/browser_tests \
+//    --gtest_filter=ExtensionWebUITest.SanityCheckAvailableAPIs
+
+// There should be a limited number of chrome.* APIs available to webui. Sanity
+// check them here.
+//
+// NOTE:  Of course, update this list if/when more APIs are made available.
+// NOTE2: Apologies to other people putting things on chrome which aren't
+//        related and whose tests fail.
+
+var expected = [
+  'csi',
+  'getVariableValue',
+  'loadTimes',
+  'runtime',
+  'send',
+  'test',
+];
+var actual = Object.keys(chrome).sort();
+
+if (!chrome.test.checkDeepEq(expected, actual)) {
+  console.error('Expected: ' + JSON.stringify(expected) + ', ' +
+                'Actual: ' + JSON.stringify(actual));
+  domAutomationController.send(false);
+} else {
+  domAutomationController.send(true);
+}