[Merge to M58] CrOS: Do not allow notifications to be added during shutdown.

chrome/browser/lifetime/application_lifetime_aura.cc

Index: chrome/browser/lifetime/application_lifetime_aura.cc
diff --git a/chrome/browser/lifetime/application_lifetime_aura.cc b/chrome/browser/lifetime/application_lifetime_aura.cc
index fd970ca3ac609c03148b9ac1b757780984460941..03d55c1da4c6fe353698e01b98e95df0290783b3 100644
--- a/chrome/browser/lifetime/application_lifetime_aura.cc
+++ b/chrome/browser/lifetime/application_lifetime_aura.cc
@@ -23,7 +23,7 @@ namespace chrome {
 void HandleAppExitingForPlatform() {
   // Close all non browser windows now. Those includes notifications
   // and windows created by Ash (launcher, background, etc).
-  g_browser_process->notification_ui_manager()->CancelAll();
+  g_browser_process->notification_ui_manager()->StartShutdown();
 
 #if defined(USE_ASH)
   // This may be called before |ash::Shell| is initialized when