Introduce ash mojo interface for lock screen action handlers

ash/shell.cc

Index: ash/shell.cc
diff --git a/ash/shell.cc b/ash/shell.cc
index 8cdfec9c861977a5c88ca323d51d7546de3f1125..a7a5138a07f352a11a57df6b23551d2124df574c 100644
--- a/ash/shell.cc
+++ b/ash/shell.cc
@@ -84,6 +84,7 @@
 #include "ash/system/tray/system_tray_delegate.h"
 #include "ash/system/tray/system_tray_notifier.h"
 #include "ash/touch/ash_touch_transform_controller.h"
+#include "ash/tray_action_handler/tray_action_handler_controller.h"
 #include "ash/utility/screenshot_controller.h"
 #include "ash/virtual_keyboard_controller.h"
 #include "ash/wallpaper/wallpaper_controller.h"
@@ -557,6 +558,8 @@ Shell::Shell(std::unique_ptr<ShellDelegate> shell_delegate,
       shutdown_controller_(base::MakeUnique<ShutdownController>()),
       system_tray_controller_(base::MakeUnique<SystemTrayController>()),
       system_tray_notifier_(base::MakeUnique<SystemTrayNotifier>()),
+      tray_action_handler_controller_(
+          base::MakeUnique<TrayActionHandlerController>()),
       vpn_list_(base::MakeUnique<VpnList>()),
       window_cycle_controller_(base::MakeUnique<WindowCycleController>()),
       window_selector_controller_(base::MakeUnique<WindowSelectorController>()),