Deal with frame removal by content scripts

chrome/test/data/extensions/api_test/executescript/destructive/remove_self.js

+// Copyright 2016 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.
+
+if (top === window) {
+  testTop();
+} else if (!parent.location.search.includes('end') ||
+    window.didRunAtDocumentEnd) {
+  testChild();
+}
+
+function testTop() {
+  var testMessage = {};
+  function reportFrames() {
+    testMessage.frameCount = frames.length;
+    testMessage.frameHTML = window.frameHTML;
+    chrome.runtime.sendMessage(testMessage);
+  }
+
+  if (window.frameHTML) {  // Set by child frame...
+    // about:blank frames are synchronously parsed, so their document_end script
+    // injection happens before the main frame's injection.
+    var expectChildBeforeMain = location.search.includes('?blankend');
+    if (!expectChildBeforeMain) {
+      // Add a message to the test notification to cause the test to fail,
+      // with some useful information for diagnostics.
+      testMessage.warning = 'Content script in child frame was executed ' +
+          'before the main frame\'s content script!';
+    }
+    reportFrames();
+  } else {
+    window.frameHTML = '(not set)';
+    window.onmessage = function(event) {
+      chrome.test.assertEq('toBeRemoved', event.data);
+      reportFrames();
+    };
+  }
+}
+
+function testChild() {
+  var TEST_HOST = parent.location.hostname;
+
+  if (TEST_HOST === 'synchronous') {
+    doRemove();
+  } else if (TEST_HOST === 'microtask') {
+    Promise.resolve().then(doRemove);
+  } else if (TEST_HOST === 'macrotask') {
+    setTimeout(doRemove, 0);
+  } else if (TEST_HOST.startsWith('domnodeinserted')) {
+    removeOnEvent('DOMNodeInserted');
+  } else if (TEST_HOST.startsWith('domsubtreemodified')) {
+    removeOnEvent('DOMSubtreeModified');
+  } else {
+    console.error('Unexpected test: ' + TEST_HOST);
+    chrome.test.fail();
+  }
+
+  function doRemove() {
+    parent.frameHTML = document.documentElement.outerHTML || '(no outerHTML)';
+    parent.postMessage('toBeRemoved', '*');
+    // frameElement = <iframe> element in parent document.
+    frameElement.remove();
+  }
+
+  function removeOnEvent(eventName) {
+    var expected = parseInt(TEST_HOST.match(/\d+/)[0]);
+    document.addEventListener(eventName, function() {
+      // Synchronously remove the frame in the mutation event.
+      if (--expected === 0)
+        doRemove();
+    });
+
+    // Fallback in case the mutation events are not triggered.
+    new Promise(function(resolve) {
+      // The window.onload event signals that the document and its resources
+      // have finished loading, so we don't expect any other parser-initiated
+      // DOM mutations after that point.
+      if (performance.timing.loadEventEnd > 0)

[Devlin, 2016/03/18 16:46:10]

nit: while this works, I think it'd be clearer to use document.readyState ===
'complete'.

[robwu, 2016/03/18 19:25:38]

Done.

+        resolve();
+      else
+        window.addEventListener('load', resolve);
+    }).then(function() {
+      if (expected > 0) {
+        expected = 0;
+        // Print this message to make it clear that the expected condition
+        // (mutation event |eventName| triggered XXX times) did not happen.
+        console.log('Mutation condition not triggered: ' + TEST_HOST);
+        doRemove();
+      }
+    });
+
+  }
+}