Wait for URLBlacklist update tasks on automation tests.

chrome/browser/net/gaia/token_service_unittest.cc

Index: chrome/browser/net/gaia/token_service_unittest.cc
diff --git a/chrome/browser/net/gaia/token_service_unittest.cc b/chrome/browser/net/gaia/token_service_unittest.cc
index 72994c69208abb016c0306f677cdebaf60933c36..b4a214a6b6b8632adf061e33c7b59c4fee1fedc3 100644
--- a/chrome/browser/net/gaia/token_service_unittest.cc
+++ b/chrome/browser/net/gaia/token_service_unittest.cc
@@ -90,10 +90,7 @@ void TokenServiceTestHarness::WaitForDBLoadCompletion() {
   // The WebDB does all work on the DB thread. This will add an event
   // to the end of the DB thread, so when we reach this task, all DB
   // operations should be complete.
-  base::WaitableEvent done(false, false);
-  BrowserThread::PostTask(
-      BrowserThread::DB, FROM_HERE, new SignalingTask(&done));
-  done.Wait();
+  CHECK(BrowserThread::WaitForPendingTasksOn(BrowserThread::DB));
 
   // Notifications should be returned from the DB thread onto the UI thread.
   message_loop_.RunAllPending();