Use EventHandler for IME

ash/host/ash_window_tree_host_x11.h

Index: ash/host/ash_window_tree_host_x11.h
diff --git a/ash/host/ash_window_tree_host_x11.h b/ash/host/ash_window_tree_host_x11.h
index 7238a08c9eff37eacea05c1fc014cdcf447b5d58..077eb43dc4de1ca3784aeb483eb704ab1230f92e 100644
--- a/ash/host/ash_window_tree_host_x11.h
+++ b/ash/host/ash_window_tree_host_x11.h
@@ -51,6 +51,12 @@ class ASH_EXPORT AshWindowTreeHostX11 : public AshWindowTreeHost,
   void OnWindowInitialized(aura::Window* window) override;
   void OnHostInitialized(aura::WindowTreeHost* host) override;
 
+  // ui::internal::InputMethodDelegate:
+  bool DispatchKeyEventPostIME(const ui::KeyEvent& event) override;
+
+  // ui::EventSource:
+  ui::EventDispatchDetails DeliverEventToProcessor(ui::Event* event) override;
+
 #if defined(OS_CHROMEOS)
   // Set the CrOS touchpad "tap paused" property. It is used to temporarily
   // turn off the Tap-to-click feature when the mouse pointer is invisible.