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

chrome/browser/extensions/extension_tabs_apitest.cc

Index: chrome/browser/extensions/extension_tabs_apitest.cc
diff --git a/chrome/browser/extensions/extension_tabs_apitest.cc b/chrome/browser/extensions/extension_tabs_apitest.cc
index ce2603c27a77915bc7655f47c0b930fa458ab059..9f74d46594d6f5e36194b00b071f8b66fe4992a1 100644
--- a/chrome/browser/extensions/extension_tabs_apitest.cc
+++ b/chrome/browser/extensions/extension_tabs_apitest.cc
@@ -76,6 +76,11 @@ IN_PROC_BROWSER_TEST_F(ExtensionApiTest, Tabs2) {
   ASSERT_TRUE(RunExtensionSubtest("tabs/basics", "crud2.html")) << message_;
 }
 
+IN_PROC_BROWSER_TEST_F(ExtensionApiTest, TabUpdate) {
+  ASSERT_TRUE(StartTestServer());
+  ASSERT_TRUE(RunExtensionSubtest("tabs/basics", "update.html")) << message_;
+}
+
 IN_PROC_BROWSER_TEST_F(ExtensionApiTest, TabPinned) {
   ASSERT_TRUE(StartTestServer());
   ASSERT_TRUE(RunExtensionSubtest("tabs/basics", "pinned.html")) << message_;