Reland: Switch WindowedNotificationObserver to use base::RunLoop.

chrome/browser/chromeos/extensions/device_local_account_external_policy_loader_unittest.cc

Index: chrome/browser/chromeos/extensions/device_local_account_external_policy_loader_unittest.cc
diff --git a/chrome/browser/chromeos/extensions/device_local_account_external_policy_loader_unittest.cc b/chrome/browser/chromeos/extensions/device_local_account_external_policy_loader_unittest.cc
index 01008ae629792fcc886525527fe5615ab92c31ae..259f34fa072f051f24da0185780a1b34504281e5 100644
--- a/chrome/browser/chromeos/extensions/device_local_account_external_policy_loader_unittest.cc
+++ b/chrome/browser/chromeos/extensions/device_local_account_external_policy_loader_unittest.cc
@@ -265,6 +265,12 @@ TEST_F(DeviceLocalAccountExternalPolicyLoaderTest, ForceInstallListSet) {
   content::WindowedNotificationObserver(
       extensions::NOTIFICATION_EXTENSION_UPDATE_FOUND,
       content::NotificationService::AllSources()).Wait();
+  // Temporary solution to mimic the old behavior of
+  // WindowedNotificationObserver.
+  // TODO(https://crbug.com/695073): Likely this has to be removed, and the
+  // IsIdleForTesting check at the end of this test has to be either changed to
+  // a more specific check or removed.
+  content::RunAllPendingInMessageLoop();
 
   // Verify that the downloader is attempting to download a CRX file.
   fetcher = factory.GetFetcherByID(