x11: Simplify some more event-rewrite code.

chrome/browser/chromeos/events/event_rewriter.h

Index: chrome/browser/chromeos/events/event_rewriter.h
diff --git a/chrome/browser/chromeos/events/event_rewriter.h b/chrome/browser/chromeos/events/event_rewriter.h
index c4a97b1aeac17f172ee7abde11c0a0887f00e36d..6c10eb5ce134020a3b1cd48a634c73e3194d1a20 100644
--- a/chrome/browser/chromeos/events/event_rewriter.h
+++ b/chrome/browser/chromeos/events/event_rewriter.h
@@ -15,24 +15,18 @@
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop/message_pump_observer.h"
 #include "chrome/browser/chromeos/device_hierarchy_observer.h"
-#include "ui/aura/window_tree_host_observer.h"
 #include "ui/events/keycodes/keyboard_codes.h"
 
 class PrefService;
 typedef union _XEvent XEvent;
 
-namespace aura {
-class RootWindow;
-}
-
 namespace chromeos {
 class KeyboardDrivenEventRewriter;
 namespace input_method {
 class XKeyboard;
 }
 
-class EventRewriter : public aura::WindowTreeHostObserver,
-                      public DeviceHierarchyObserver,
+class EventRewriter : public DeviceHierarchyObserver,
                       public base::MessagePumpObserver {
  public:
   enum DeviceType {
@@ -69,10 +63,6 @@ class EventRewriter : public aura::WindowTreeHostObserver,
   friend class EventRewriterAshTest;
   friend class EventRewriterTest;
 
-  // aura::WindowTreeHostObserver overrides:
-  virtual void OnKeyboardMappingChanged(
-      const aura::WindowTreeHost* host) OVERRIDE;
-
   // base::MessagePumpObserver overrides:
   virtual base::EventStatus WillProcessEvent(
       const base::NativeEvent& event) OVERRIDE;