Wait for URLBlacklist update tasks on automation tests.

chrome/browser/extensions/test_extension_prefs.cc

Index: chrome/browser/extensions/test_extension_prefs.cc
diff --git a/chrome/browser/extensions/test_extension_prefs.cc b/chrome/browser/extensions/test_extension_prefs.cc
index a8eb4445174542d689f2a17d951ee1f88d61d215..6f72d56bb755031d69ff8a2a5687ff5dba771556 100644
--- a/chrome/browser/extensions/test_extension_prefs.cc
+++ b/chrome/browser/extensions/test_extension_prefs.cc
@@ -9,7 +9,6 @@
 #include "base/message_loop.h"
 #include "base/message_loop_proxy.h"
 #include "base/values.h"
-#include "base/synchronization/waitable_event.h"
 #include "chrome/browser/extensions/extension_pref_store.h"
 #include "chrome/browser/extensions/extension_pref_value_map.h"
 #include "chrome/browser/extensions/extension_prefs.h"
@@ -19,7 +18,6 @@
 #include "chrome/common/extensions/extension.h"
 #include "chrome/common/extensions/extension_constants.h"
 #include "chrome/common/json_pref_store.h"
-#include "chrome/test/base/signaling_task.h"
 #include "content/browser/browser_thread.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ -69,18 +67,12 @@ void TestExtensionPrefs::RecreateExtensionPrefs() {
     // The PrefService writes its persistent file on the file thread, so we
     // need to wait for any pending I/O to complete before creating a new
     // PrefService.
-    base::WaitableEvent io_finished(false, false);
     pref_service_->SavePersistentPrefs();
-    EXPECT_TRUE(BrowserThread::PostTask(BrowserThread::FILE, FROM_HERE,
-                                        new SignalingTask(&io_finished)));
-
-    // If the FILE thread is in fact the current thread (possible in testing
-    // scenarios), we have to ensure the task has a chance to run. If the FILE
-    // thread is a different thread, the test must ensure that thread is running
-    // (otherwise the Wait below will hang).
-    MessageLoop::current()->RunAllPending();
-
-    io_finished.Wait();
+    if (!BrowserThread::WaitForPendingTasksOn(BrowserThread::DB)) {
+      // If the FILE thread is in fact the current thread (possible in testing
+      // scenarios), we have to ensure the task is executed before proceeding.
+      MessageLoop::current()->RunAllPending();
+    }
   }
 
   extension_pref_value_map_.reset(new ExtensionPrefValueMap);