Revert of Remove InputMethodEventHandler.

ash/host/ash_window_tree_host_unified.cc

 // Copyright 2015 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.
 
 #include "ash/host/ash_window_tree_host_unified.h"
 
 #include <utility>
 
 #include "ash/host/root_window_transformer.h"
+#include "ash/ime/input_method_event_handler.h"
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
 #include "ui/aura/window.h"
 #include "ui/aura/window_event_dispatcher.h"
 #include "ui/aura/window_targeter.h"
 #include "ui/compositor/compositor.h"
 #include "ui/gfx/geometry/insets.h"
 #include "ui/platform_window/stub/stub_window.h"
 
 namespace ash {
@@ skipping 82 matching lines @@
       std::find_if(mirroring_hosts_.begin(), mirroring_hosts_.end(),
                    [window](AshWindowTreeHost* ash_host) {
                      return ash_host->AsWindowTreeHost()->window() == window;
                    });
   DCHECK(iter != mirroring_hosts_.end());
   window->RemoveObserver(this);
   mirroring_hosts_.erase(iter);
 }
 
 }  // namespace ash