Make chrome.tabs.update's tabId parameter optional.

chrome/test/data/extensions/api_test/tabs/basics/update.js

+// Copyright (c) 2011 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.
+
+var tabIds = [];
+var kFooUrl = "foo";
+var kBarUrl = "bar";
+
+chrome.test.runTests([
+  function setUp() {
+    chrome.tabs.create({"url": pageUrl("a")}, function(tab) {
+      tabIds.push(tab.id);
+    });
+    chrome.tabs.create({"url": pageUrl("b")}, function(tab) {
+      tabIds.push(tab.id);
+    });
+    chrome.tabs.create({"url": pageUrl("c")}, function(tab) {
+      tabIds.push(tab.id);
+    });
+    chrome.windows.create({"url": pageUrl("xxx")}, pass(function(tab) {}));
+  },
+
+  function testBasicSetup() {
+    chrome.tabs.get(tabIds[0], pass(function(tab) {
+      assertEq(pageUrl("a"), tab.url);
+    }));
+    chrome.tabs.get(tabIds[1], pass(function(tab) {
+      assertEq(pageUrl("b"), tab.url);
+    }));
+    chrome.tabs.get(tabIds[2], pass(function(tab) {
+      assertEq(pageUrl("c"), tab.url);
+    }));
+  },
+
+  function testUpdatingDefaultTabViaUndefined() {
+    chrome.tabs.update(
+      tabIds[1],
+      {"selected": true},
+      pass(function(tab) {
+        chrome.tabs.update(
+          undefined,
+          {"url": pageUrl(kFooUrl)},
+          pass(function(tab) {
+            chrome.tabs.get(
+              tabIds[1],
+              pass(function(tab) {
+                assertEq(pageUrl(kFooUrl), tab.url);
+              }));
+          }));
+      }));
+  },
+
+  function testUpdatingDefaultTabViaNull() {
+    chrome.tabs.update(
+      tabIds[2],
+      {"selected": true},
+      pass(function(tab) {
+        chrome.tabs.update(
+          null,
+          {"url": pageUrl(kBarUrl)},
+          pass(function(tab) {
+            chrome.tabs.get(
+              tabIds[2],
+              pass(function(tab) {
+                assertEq(pageUrl(kBarUrl), tab.url);
+              }));
+          }));
+      }));
+  }
+]);