[Extensions] Don't allow content scripts on the New Tab Page

chrome/test/data/extensions/api_test/content_scripts/ntp/background.js

+// Copyright 2017 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 testExecuteScriptInNewTab() {
+  // Create a new tab to chrome://newtab and wait for the loading to complete.
+  // Then, try to inject a script into that tab. The injection should fail.
+  chrome.tabs.onUpdated.addListener(function listener(tabId, changeInfo, tab) {
+    if (tab.url != 'chrome://newtab/' || changeInfo.status != 'complete')
+      return;
+    chrome.tabs.onUpdated.removeListener(listener);
+    chrome.tabs.executeScript(tab.id, {file: 'script.js'}, function() {
+      chrome.test.assertTrue(!!chrome.runtime.lastError);
+      chrome.test.assertTrue(
+          chrome.runtime.lastError.message.indexOf(
+              'Cannot access contents of') != -1,
+          chrome.runtime.lastError.message);
+      chrome.test.succeed();
+    });
+  });
+  chrome.tabs.create({url: 'chrome://newtab'});
+}
+
+chrome.test.sendMessage('ready', function() {
+  chrome.test.runTests([testExecuteScriptInNewTab]);
+});