Pass load events from prerenders to launching elements.

chrome/test/data/prerender/prerender_events_common.js

Index: chrome/test/data/prerender/prerender_events_common.js
diff --git a/chrome/test/data/prerender/prerender_events_common.js b/chrome/test/data/prerender/prerender_events_common.js
new file mode 100644
index 0000000000000000000000000000000000000000..e6f64cf06d3d1cf8cb12dc8b24f092dbe0ee2daf
--- /dev/null
+++ b/chrome/test/data/prerender/prerender_events_common.js
@@ -0,0 +1,46 @@
+// 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.
+
+// Common js for prerender loaders; defines the helper functions that put
+// event handlers on prerenders and track the events for browser tests.
+
+// TODO(gavinp): Put more common loader logic in here.
+
+var hadPrerenderEventErrors = false;

[mmenke, 2012/12/27 19:11:08]

Think it's worth having a comment that enumerates the errors it detects
(Currently just event ordering errors, of course).  If you think it's unlikely
we'll ever be looking for other errors, could just rename it to
"hadPrerenderEventOrderingErrors".

[gavinp, 2012/12/28 13:23:15]

Done.

+var receivedPrerenderStartEvents = [];
+var receivedPrerenderLoadEvents = [];
+var receivedPrerenderStopEvents = [];
+
+function PrerenderStartHandler(index) {
+  if (receivedPrerenderStartEvents[index] ||
+      receivedPrerenderLoadEvents[index] ||
+      receivedPrerenderStopEvents[index]) {
+    hadPrerenderEventErrors = true;
+    return;
+  }
+  receivedPrerenderStartEvents[index] = true;
+}
+
+function PrerenderLoadHandler(index) {
+  if (!receivedPrerenderStartEvents[index] ||
+      receivedPrerenderLoadEvents[index] ||
+      receivedPrerenderStopEvents[index]) {
+    hadPrerenderEventErrors = true;
+    return;
+  }
+  receivedPrerenderLoadEvents[index] = true;
+}
+
+function PrerenderStopHandler(index) {
+  receivedPrerenderStopEvents[index] = true;

[mmenke, 2012/12/27 19:11:08]

Just for completeness, suggest checking to make sure we've received the start
event, and not received the stop event.  That way, we could actually test just
hadPrerenderEventErrors on all tests, if we want, and have a little more test
coverage.

[gavinp, 2012/12/28 13:23:15]

Done. Good thinking.

+}
+
+function AddEventHandlersToLinkElement(link, index) {
+  link.addEventListener('webkitprerenderstart',
+                        PrerenderStartHandler.bind(null, index), false);
+  link.addEventListener('webkitprerenderload',
+                        PrerenderLoadHandler.bind(null, index), false);
+  link.addEventListener('webkitprerenderstop',
+                        PrerenderStopHandler.bind(null, index), false);
+}