Do not watch for low disk events in guest mode.

chrome/browser/chromeos/chrome_browser_main_chromeos.cc

Index: chrome/browser/chromeos/chrome_browser_main_chromeos.cc
diff --git a/chrome/browser/chromeos/chrome_browser_main_chromeos.cc b/chrome/browser/chromeos/chrome_browser_main_chromeos.cc
index d2acdd20c68609a5555b6b83898abe758ecb170d..f78c69e29a638dd46d72e5b5c5e6642fbbf79a62 100644
--- a/chrome/browser/chromeos/chrome_browser_main_chromeos.cc
+++ b/chrome/browser/chromeos/chrome_browser_main_chromeos.cc
@@ -688,8 +688,10 @@ void ChromeBrowserMainPartsChromeos::PostProfileInit() {
   // available.
   idle_action_warning_observer_.reset(new IdleActionWarningObserver());
 
-  // Start watching for low disk space events to notify the user.
-  low_disk_notification_.reset(new LowDiskNotification());
+  // Start watching for low disk space events to notify the user if it is not a
+  // guest profile.
+  if (!user_manager::UserManager::Get()->IsLoggedInAsGuest())
+    low_disk_notification_.reset(new LowDiskNotification());
 
   // Authenticate the user for PIN quick unlock.
   PinStorage* pin_storage = PinStorageFactory::GetForProfile(profile());