aura: Remove client::UserActionClient.

ash/shell.h

Index: ash/shell.h
diff --git a/ash/shell.h b/ash/shell.h
index bc318f085ce45c94edfef8b7d0b1dcb00eb1c781..6bb3be0e26a52ad14cf9c23967dead30e0d1b80c 100644
--- a/ash/shell.h
+++ b/ash/shell.h
@@ -40,7 +40,6 @@ class Window;
 namespace client {
 class ActivationClient;
 class FocusClient;
-class UserActionClient;
 }
 }
 namespace chromeos {
@@ -666,7 +665,6 @@ class ASH_EXPORT Shell
   scoped_ptr<PartialMagnificationController> partial_magnification_controller_;
   scoped_ptr<AutoclickController> autoclick_controller_;
   scoped_ptr<aura::client::FocusClient> focus_client_;
-  scoped_ptr<aura::client::UserActionClient> user_action_client_;
   aura::client::ActivationClient* activation_client_;
   scoped_ptr<internal::MouseCursorEventFilter> mouse_cursor_filter_;
   scoped_ptr<internal::ScreenPositionController> screen_position_controller_;