Address ExtensionApiTest.Tabs flakiness

chrome/renderer/resources/extension_apitest.js

 // extension_apitest.js
 // mini-framework for ExtensionApiTest browser tests
 
 var chrome = chrome || {};
 (function() {
   chrome.test = chrome.test || {};
 
   chrome.test.tests = chrome.test.tests || [];
 
   var completed = false;
@@ skipping 30 matching lines @@
     complete();
   };
 
   function allTestsSucceeded() {
     console.log("All tests succeeded");
     if (completed) throw "completed";
 
     chrome.test.notifyPass();
     complete();
   }
-
+  
   var pendingCallbacks = 0;
 
-  function callbackAdded() {
+  chrome.test.callbackAdded = function () {
     pendingCallbacks++;
-  };
 
-  function callbackCompleted() {
-    pendingCallbacks--;
-    if (pendingCallbacks == 0) {
-      chrome.test.succeed();
+    return function() {
+      pendingCallbacks--;
+      if (pendingCallbacks == 0) {
+        chrome.test.succeed();
+      }
     }
   };
 
   chrome.test.runNextTest = function() {
     chrome.test.assertEq(pendingCallbacks, 0);
     lastTest = currentTest;
     currentTest = chrome.test.tests.shift();
     if (!currentTest) {
       allTestsSucceeded();
       return;
@@ skipping 69 matching lines @@
       chrome.test.fail(msg);
     }
   };
 
   // Wrapper for generating test functions, that takes care of calling
   // assertNoLastError() and (optionally) succeed() for you.
   chrome.test.callback = function(func, expectedError) {
     if (func) {
       chrome.test.assertEq(typeof(func), 'function');
     }
-    callbackAdded();
+    var callbackCompleted = chrome.test.callbackAdded();
 
     return function() {
       if (expectedError == null) {
         chrome.test.assertNoLastError();
       } else {
         chrome.test.assertEq(typeof(expectedError), 'string');
         chrome.test.assertEq(expectedError, chrome.extension.lastError.message);
       }
       
       if (func) {
         safeFunctionApply(func, arguments);
       }
 
       callbackCompleted();
     };
   };
 
   chrome.test.listenOnce = function(event, func) {
-    callbackAdded();
+    var callbackCompleted = chrome.test.callbackAdded();
     var listener = function() {
       event.removeListener(listener);
       safeFunctionApply(func, arguments);
       callbackCompleted();
     };
     event.addListener(listener);
   };
   
   chrome.test.listenForever = function(event, func) {
-    callbackAdded();
-    
+    var callbackCompleted = chrome.test.callbackAdded();
+ 
     var listener = function() {
       safeFunctionApply(func, arguments);
     };
 
-    var done = {};
-    done.doneListening = function() {
+    var done = function() {
       event.removeListener(listener);
       callbackCompleted();
     };
  
     event.addListener(listener);
     return done;
   };
 
   chrome.test.callbackPass = function(func) {
     return chrome.test.callback(func);
   };
 
   chrome.test.callbackFail = function(expectedError) {
     return chrome.test.callback(null, expectedError);
   };
 
   chrome.test.runTests = function(tests) {
     chrome.test.tests = tests;
     chrome.test.runNextTest();
   };
 })();