Adding infrastructure for possibility of changing manager names for the supervised accounts.

ash/system/tray/default_system_tray_delegate.h

Index: ash/system/tray/default_system_tray_delegate.h
diff --git a/ash/system/tray/default_system_tray_delegate.h b/ash/system/tray/default_system_tray_delegate.h
index bbac7ba400249c4e6aa475c9cd91ae3f8a517826..72d1c401b2bd13f0794dfd9bcdd1c0e8539a11f9 100644
--- a/ash/system/tray/default_system_tray_delegate.h
+++ b/ash/system/tray/default_system_tray_delegate.h
@@ -88,6 +88,10 @@ class ASH_EXPORT DefaultSystemTrayDelegate : public SystemTrayDelegate {
   virtual bool IsSearchKeyMappedToCapsLock() override;
   virtual tray::UserAccountsDelegate* GetUserAccountsDelegate(
       const std::string& user_id) override;
+  virtual void AddCustodianInfoTrayObserver(
+      CustodianInfoTrayObserver* observer) override;
+  virtual void RemoveCustodianInfoTrayObserver(
+      CustodianInfoTrayObserver* observer) override;
 
  private:
   bool bluetooth_enabled_;