Drop the const modifier on NotificationDisplayService::GetDisplayed

chrome/browser/notifications/notification_display_service.h

Index: chrome/browser/notifications/notification_display_service.h
diff --git a/chrome/browser/notifications/notification_display_service.h b/chrome/browser/notifications/notification_display_service.h
index 1eeada650f22bb32015db13500370a95d5508fca..92cf5ece841ca2d46495260c1e2cef23531108a9 100644
--- a/chrome/browser/notifications/notification_display_service.h
+++ b/chrome/browser/notifications/notification_display_service.h
@@ -42,8 +42,7 @@ class NotificationDisplayService : public KeyedService {
 
   // Writes the ids of all currently displaying notifications and
   // invokes |callback| with the result once known.
-  virtual void GetDisplayed(
-      const DisplayedNotificationsCallback& callback) const = 0;
+  virtual void GetDisplayed(const DisplayedNotificationsCallback& callback) = 0;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(NotificationDisplayService);