Separates out accelerator handling in windowmanager

ash/mus/window_manager_observer.h

Index: ash/mus/window_manager_observer.h
diff --git a/ash/mus/window_manager_observer.h b/ash/mus/window_manager_observer.h
index 0fa0982aaaad77ada6cecd37737cb3c08a088f1e..e5c5070bb6b5c75b9e3335bbddd0f6d06bb236f6 100644
--- a/ash/mus/window_manager_observer.h
+++ b/ash/mus/window_manager_observer.h
@@ -5,12 +5,6 @@
 #ifndef ASH_MUS_WINDOW_OBSERVER_H_
 #define ASH_MUS_WINDOW_OBSERVER_H_
 
-#include <stdint.h>
-
-namespace ui {
-class Event;
-}
-
 namespace ash {
 namespace mus {
 
@@ -22,8 +16,6 @@ class WindowManagerObserver {
   // about to be destroyed.
   virtual void OnWindowTreeClientDestroyed() {}
 
-  virtual void OnAccelerator(uint32_t id, const ui::Event& event) {}
-
   virtual void OnRootWindowControllerAdded(RootWindowController* controller) {}
   virtual void OnWillDestroyRootWindowController(
       RootWindowController* controller) {}