Revert of Remove InputMethodEventHandler.

ash/host/ash_window_tree_host.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef ASH_HOST_ASH_WINDOW_TREE_HOST_H_
 #define ASH_HOST_ASH_WINDOW_TREE_HOST_H_
 
 #include <memory>
 
 #include "ash/ash_export.h"
 
 namespace aura {
 class WindowTreeHost;
 }
 
 namespace gfx {
 class Insets;
 }
 
 namespace ui {
 class LocatedEvent;
 }
 
 namespace ash {
 struct AshWindowTreeHostInitParams;
+class InputMethodEventHandler;
 class RootWindowTransformer;
 
 class ASH_EXPORT AshWindowTreeHost {
  public:
   AshWindowTreeHost();
   virtual ~AshWindowTreeHost();
 
   static std::unique_ptr<AshWindowTreeHost> Create(
       const AshWindowTreeHostInitParams& init_params);
 
+  void set_input_method_handler(InputMethodEventHandler* input_method_handler) {
+    input_method_handler_ = input_method_handler;
+  }
+
+  InputMethodEventHandler* input_method_handler() {
+    return input_method_handler_;
+  }
+
   // Toggles the host's full screen state.
   virtual void ToggleFullScreen() = 0;
 
   // Clips the cursor to the bounds of the root window until UnConfineCursor().
   // We would like to be able to confine the cursor to that window. However,
   // currently, we do not have such functionality in X. So we just confine
   // to the root window. This is ok because this option is currently only
   // being used in fullscreen mode, so root_window bounds = window bounds.
   virtual bool ConfineCursorToRootWindow() = 0;
   virtual void UnConfineCursor() = 0;
 
   virtual void SetRootWindowTransformer(
       std::unique_ptr<RootWindowTransformer> transformer) = 0;
 
   virtual gfx::Insets GetHostInsets() const = 0;
 
   virtual aura::WindowTreeHost* AsWindowTreeHost() = 0;
 
   // Stop listening for events in preparation for shutdown.
   virtual void PrepareForShutdown() {}
 
   virtual void RegisterMirroringHost(AshWindowTreeHost* mirroring_ash_host) {}
 
  protected:
   // Translates the native mouse location into screen coordinates.
   void TranslateLocatedEvent(ui::LocatedEvent* event);
+
+ private:
+  InputMethodEventHandler* input_method_handler_;
 };
 
 }  // namespace ash
 
 #endif  // ASH_HOST_ASH_WINDOW_TREE_HOST_H_