Add a test helper class for ExtensionRegistry.

chrome/browser/extensions/extension_storage_monitor_browsertest.cc

Index: chrome/browser/extensions/extension_storage_monitor_browsertest.cc
diff --git a/chrome/browser/extensions/extension_storage_monitor_browsertest.cc b/chrome/browser/extensions/extension_storage_monitor_browsertest.cc
index 1c32600bdcaf19a3d5397821ca240bddb11604e1..aec6d0f37119a4c38697663e910e38238165f563 100644
--- a/chrome/browser/extensions/extension_storage_monitor_browsertest.cc
+++ b/chrome/browser/extensions/extension_storage_monitor_browsertest.cc
@@ -13,7 +13,9 @@
 #include "chrome/browser/ui/extensions/application_launch.h"
 #include "content/public/test/test_utils.h"
 #include "extensions/browser/extension_prefs.h"
+#include "extensions/browser/extension_registry.h"
 #include "extensions/browser/extension_system.h"
+#include "extensions/browser/test_extension_registry_observer.h"
 #include "ui/message_center/message_center.h"
 #include "ui/message_center/message_center_observer.h"
 
@@ -332,11 +334,10 @@ IN_PROC_BROWSER_TEST_F(ExtensionStorageMonitorTest, UninstallExtension) {
       ExtensionStorageMonitor::BUTTON_UNINSTALL);
 
   // Also fake accepting the uninstall.
-  content::WindowedNotificationObserver uninstalled_signal(
-      chrome::NOTIFICATION_EXTENSION_UNINSTALLED_DEPRECATED,
-      content::Source<Profile>(profile()));
+  extensions::TestExtensionRegistryObserver observer(

[Lei Zhang, 2014/06/19 23:48:10]

ditto, already in the extensions namespace

[limasdf, 2014/06/20 14:04:27]

Done.

+      extensions::ExtensionRegistry::Get(profile()), extension->id());
   SimulateUninstallDialogAccept();
-  uninstalled_signal.Wait();
+  observer.WaitForExtensionUninstalled();
 }
 
 }  // namespace extensions