Add ref count to service workers for extension API.

chrome/browser/extensions/service_worker_apitest.cc

Index: chrome/browser/extensions/service_worker_apitest.cc
diff --git a/chrome/browser/extensions/service_worker_apitest.cc b/chrome/browser/extensions/service_worker_apitest.cc
index 2c9e0eef1de88058f76a29a436a5670cb472c838..0eb1b14f469ae9ee70ec1f8b2e9ae37355d5aa4c 100644
--- a/chrome/browser/extensions/service_worker_apitest.cc
+++ b/chrome/browser/extensions/service_worker_apitest.cc
@@ -612,7 +612,7 @@ IN_PROC_BROWSER_TEST_F(ServiceWorkerTest, TabsCreate) {
   std::string result;
   ASSERT_TRUE(content::ExecuteScriptAndExtractString(
       web_contents, "window.runServiceWorker()", &result));
-  ASSERT_EQ("chrome.tabs.create callback", result);
+  ASSERT_EQ("chrome.tabs.update callback", result);
   EXPECT_EQ(starting_tab_count + 1, browser()->tab_strip_model()->count());
 
   // Check extension shutdown path.