Simplify AjaxCounterBean

Based on revised code from http://stackoverflow.com/a/4411986/14379

Also removing setTimeout support: the timeoutCounter is not used, and
  the wrapper code is causing problems.

functional-test/src/main/java/org/zanata/page/AbstractPage.java

@@ -185,30 +185,13 @@ public boolean apply(WebDriver input) {
         logFinished(msg);
     }
 
-    /**
-     * Wait for any AJAX and timeout requests to return.
-     */
-    public void waitForAbsolutePageSilence() {
-        waitForPageSilence(true);
-    }
-
-    /**
-     * Wait for any AJAX (but not timeout) requests to return.
-     */
-    public void waitForPageSilence() {
-        waitForPageSilence(false);
-    }
-
     /**
      * Wait for any AJAX/timeout requests to return.
      */
-    private void waitForPageSilence(boolean includingTimeouts) {
-        final String script;
-        if (includingTimeouts) {
-            script = "return XMLHttpRequest.active + window.timeoutCounter";
-        } else {
-            script = "return XMLHttpRequest.active";
-        }
+    public void waitForPageSilence() {
+        // TODO wait for any short-lived timeouts to expire (eg less than 1000 ms)
+        // but not multi-second timeouts (eg global faces messages)
+        final String script = "return XMLHttpRequest.active";
         // Wait for AJAX/timeout requests to be 0
         waitForAMoment().withMessage("page silence").until(new Predicate<WebDriver>() {
             @Override

zanata-war/src/main/java/org/zanata/action/AjaxCounterBean.java

@@ -34,40 +34,27 @@
 @Name("ajaxCounter")
 @Slf4j
 public class AjaxCounterBean {
+    // NB this doesn't handle setInterval or setTimeout
+    // TODO handle XHR.abort (NB: readystatechange listener triggers on Chrome 45, despite MDN docs)
     // http://stackoverflow.com/questions/4410218/trying-to-keep-track-of-number-of-outstanding-ajax-requests-in-firefox
-    private static final String AJAX_COUNTER_SCRIPT = "<script type=\"application/javascript\">" +
+    private static final String AJAX_COUNTER_SCRIPT = "<script type=\"application/javascript\">\n" +
             "(function(xhr) {\n" +
-            "  if (xhr.active === undefined) {\n" +
-            "    xhr.active = 0;\n" +
-            "    var pt = xhr.prototype;\n" +
-            "    pt._send = pt.send;\n" +
-            "    pt.send = function() {\n" +
-            "        XMLHttpRequest.active++;\n" +
-            "        this._onreadystatechange = this.onreadystatechange;\n" +
-            "        this.onreadystatechange = function(e) {\n" +
-            "            if ( this._onreadystatechange ) {\n" +
-            "                var fn = this._onreadystatechange.handleEvent || this._onreadystatechange;\n" +
-            "                fn.apply(this, arguments);\n" +
-            "            }\n" +
-            "            if ( this.readyState == 4 ) {\n" +
-            "                XMLHttpRequest.active--;\n" +
-            "            }\n" +
-            "        };\n" +
-            "        this._send.apply(this, arguments);\n" +
+            "    if (xhr.active === undefined) {\n" +
+            "        xhr.active = 0;\n" +
+            "        var pt = xhr.prototype;\n" +
+            "        var _send = pt.send;\n" +
+            "        pt.send = function() {\n" +
+            "            xhr.active++;\n" +
+            "            this.addEventListener('readystatechange', function(e) {\n" +
+            "                if ( this.readyState == XMLHttpRequest.DONE ) {\n" +
+            "                    setTimeout(function() {\n" +
+            "                        xhr.active--;\n" +
+            "                    }, 1);\n" +
+            "                }\n" +
+            "            });\n" +
+            "            _send.apply(this, arguments);\n" +
+            "        }\n" +
             "    }\n" +
-            "    window.timeoutCounter = 0;\n" +
-            "    window.originalSetTimeout = window.setTimeout;\n" +
-            "    window.setTimeout = function(func, delay, params) {\n" +
-            "        window.timeoutCounter++;\n" +
-            "        window.originalSetTimeout(window.timeoutCallback, delay, [func, params]);\n" +
-            "    }\n" +
-            "    window.timeoutCallback = function(funcAndParams) {\n" +
-            "        window.timeoutCounter--;\n" +
-            "        func = funcAndParams[0];\n" +
-            "        params = funcAndParams[1];\n" +
-            "        func(params);\n" +
-            "    }\n" +
-            "  }\n" +
             "})(XMLHttpRequest);\n" +
             "</script>\n";