Don't show system notifications while the screen is locked.

chrome/browser/chromeos/extensions/file_browser_notifications_browsertest.cc

Index: chrome/browser/chromeos/extensions/file_browser_notifications_browsertest.cc
diff --git a/chrome/browser/chromeos/extensions/file_browser_notifications_browsertest.cc b/chrome/browser/chromeos/extensions/file_browser_notifications_browsertest.cc
index 3b41a46bc3ebbdf33297fbe6c0ce1ef4d50a429d..bb2f99d4ff142728fc30b77e97471a9925d13bc0 100644
--- a/chrome/browser/chromeos/extensions/file_browser_notifications_browsertest.cc
+++ b/chrome/browser/chromeos/extensions/file_browser_notifications_browsertest.cc
@@ -76,6 +76,10 @@ class FileBrowserNotificationsTest : public InProcessBrowserTest {
  public:
   FileBrowserNotificationsTest() : collection_(NULL) {}
 
+  virtual void CleanUpOnMainThread() OVERRIDE {
+    notifications_.reset();
+  }
+
  protected:
   // This must be initialized late in test startup.
   void InitNotifications() {