Add browser tests for extensions tab API.

chrome/test/data/extensions/api_test/bookmarks/test.js

 // bookmarks api test
 // browser_tests.exe --gtest_filter=ExtensionApiTest.Bookmarks
 
 var expected = [
   {"children": [
     {"children": [], "id": "1", "parentId": "0", "index": 0, "title":"Bookmarks bar"},
     {"children": [], "id": "2", "parentId": "0", "index": 1, "title":"Other bookmarks"}
     ],
    "id": "0", "title": ""
   }
 ];
 
+var testCallback = chrome.test.testCallback;
+
 function compareNode(left, right) {
   //console.log(JSON.stringify(left));
   //console.log(JSON.stringify(right));
   // TODO(erikkay): do some comparison of dateAdded
   if (left.id != right.id)
     return "id mismatch: " + left.id + " != " + right.id;
   if (left.title != right.title)
     return "title mismatch: " + left.title + " != " + right.title;
   if (left.url != right.url)
     return "url mismatch: " + left.url + " != " + right.url;
@@ skipping 22 matching lines @@
     }
     result = compareTrees(left[i].children, right[i].children);
     if (result !== true)
       return result;
   }
   return true;
 }
 
 chrome.test.runTests([
   function getTree() {
-    chrome.bookmarks.getTree(chrome.test.testFunction(function(results) {
+    chrome.bookmarks.getTree(testCallback(true, function(results) {
       chrome.test.assertTrue(compareTrees(results, expected),
                  "getTree() result != expected");
       expected = results;
     }));
   },
 
   function get() {
-    chrome.bookmarks.get("1", chrome.test.testFunction(function(results) {
+    chrome.bookmarks.get("1", testCallback(true, function(results) {
       chrome.test.assertTrue(compareNode(results[0], expected[0].children[0]));
     }));
   },
 
   function getArray() {
-    chrome.bookmarks.get(["1", "2"], 
-                         chrome.test.testFunction(function(results) {
+    chrome.bookmarks.get(["1", "2"], testCallback(true, function(results) {
       chrome.test.assertTrue(compareNode(results[0], expected[0].children[0]),
                  "get() result != expected");
       chrome.test.assertTrue(compareNode(results[1], expected[0].children[1]),
                  "get() result != expected");
     }));
   },
 
   function getChildren() {
-    chrome.bookmarks.getChildren("0",
-                                 chrome.test.testFunction(function(results) {
+    chrome.bookmarks.getChildren("0", testCallback(true, function(results) {
       chrome.test.assertTrue(compareNode(results[0], expected[0].children[0]),
                  "getChildren() result != expected");
       chrome.test.assertTrue(compareNode(results[1], expected[0].children[1]),
                  "getChildren() result != expected");
     }));
   },
 
   function create() {
     var node = {parentId: "1", title:"google", url:"http://www.google.com/"};
-    chrome.bookmarks.create(node, chrome.test.testFunction(function(results) {
+    chrome.bookmarks.create(node, testCallback(true, function(results) {
       node.id = results.id;  // since we couldn't know this going in
       node.index = 0;
       chrome.test.assertTrue(compareNode(node, results),
                  "created node != source");
     }));
   },
 ]);