Enable <webview>.executeScript outside of Apps and Extensions [1]

chrome/test/data/webui/webview_execute_script_test.js

+// Copyright 2015 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.
+
+function createWebview() {
+  var webview = document.createElement('webview');
+  document.body.appendChild(webview);
+  return webview;
+}
+
+function testExecuteScriptCode(url) {
+  var webview = createWebview();
+
+  var onGetBackgroundExecuted = function(results) {
+    chrome.send('testResult', [results.length == 1 && results[0] == 'red']);
+  };
+
+  var onSetBackgroundExecuted = function() {
+    webview.executeScript({
+      code: 'document.body.style.backgroundColor;'
+    }, onGetBackgroundExecuted);
+  };
+
+  var onLoadStop = function() {
+    webview.executeScript({
+      code: 'document.body.style.backgroundColor = \'red\';'
+    }, onSetBackgroundExecuted);
+  };
+
+  webview.addEventListener('loadstop', onLoadStop);
+  webview.src = url;
+}