chromeos: Migrate SignOut and RequestRestartForUpdate to mojo interface

ash/common/system/user/user_view.cc

Index: ash/common/system/user/user_view.cc
diff --git a/ash/common/system/user/user_view.cc b/ash/common/system/user/user_view.cc
index 8290fb1bc1b7ca11e6e1448103a1f0c61a199651..817a9017f5eed8e485145aa5ebe35355b5e21d61 100644
--- a/ash/common/system/user/user_view.cc
+++ b/ash/common/system/user/user_view.cc
@@ -13,6 +13,7 @@
 #include "ash/common/session/session_state_delegate.h"
 #include "ash/common/shell_delegate.h"
 #include "ash/common/system/tray/system_tray.h"
+#include "ash/common/system/tray/system_tray_controller.h"
 #include "ash/common/system/tray/system_tray_delegate.h"
 #include "ash/common/system/tray/tray_constants.h"
 #include "ash/common/system/tray/tray_popup_label_button.h"
@@ -381,7 +382,7 @@ void UserView::ButtonPressed(views::Button* sender, const ui::Event& event) {
   if (sender == logout_button_) {
     WmShell::Get()->RecordUserMetricsAction(UMA_STATUS_AREA_SIGN_OUT);
     RemoveAddUserMenuOption();
-    WmShell::Get()->system_tray_delegate()->SignOut();
+    WmShell::Get()->system_tray_controller()->SignOut();
   } else if (sender == user_card_view_ &&
              IsMultiProfileSupportedAndUserActive()) {
     if (IsActiveUser()) {