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 c45bc4aa3f6c818ae15dd6a6683b2472d2438cb0..4d22b1702df861712ec5b771cef5a178257a697e 100644
--- a/ash/shell.cc
+++ b/ash/shell.cc
@@ -14,6 +14,7 @@
 #include "ash/accelerators/magnifier_key_scroller.h"
 #include "ash/accelerators/spoken_feedback_toggler.h"
 #include "ash/accessibility_delegate.h"
+#include "ash/action_handler/action_handler_state_controller.h"
 #include "ash/app_list/app_list_delegate_impl.h"
 #include "ash/ash_constants.h"
 #include "ash/aura/shell_port_classic.h"
@@ -549,6 +550,8 @@ void Shell::NotifyShelfAutoHideBehaviorChanged(WmWindow* root_window) {
 Shell::Shell(std::unique_ptr<ShellDelegate> shell_delegate,
              std::unique_ptr<ShellPort> shell_port)
     : shell_port_(std::move(shell_port)),
+      action_handler_state_controller_(
+          base::MakeUnique<ActionHandlerStateController>()),
       brightness_control_delegate_(
           base::MakeUnique<system::BrightnessControllerChromeos>()),
       cast_config_(base::MakeUnique<CastConfigController>()),