[Code cleanup]Remove webui keyboard mojo binding

ui/keyboard/webui/vk_mojo_handler.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 UI_KEYBOARD_WEBUI_VK_MOJO_HANDLER_H_
-#define UI_KEYBOARD_WEBUI_VK_MOJO_HANDLER_H_
-
-#include "base/macros.h"
-#include "third_party/mojo/src/mojo/public/cpp/bindings/binding.h"
-#include "ui/base/ime/input_method_observer.h"
-#include "ui/keyboard/webui/keyboard.mojom.h"
-
-namespace keyboard {
-
-class VKMojoHandler : public KeyboardUIHandlerMojo,
-                      public ui::InputMethodObserver {
- public:
-  explicit VKMojoHandler(mojo::InterfaceRequest<KeyboardUIHandlerMojo> request);
-  ~VKMojoHandler() override;
-
- private:
-  ui::InputMethod* GetInputMethod();
-
-  // KeyboardUIHandlerMojo:
-  void SetTextInputTypeObserver(TextInputTypeObserverPtr observer) override;
-  void SendKeyEvent(const mojo::String& event_type,
-                    int32_t char_value,
-                    int32_t key_code,
-                    const mojo::String& key_name,
-                    int32_t modifiers) override;
-  void HideKeyboard() override;
-
-  // ui::InputMethodObserver:
-  void OnTextInputTypeChanged(const ui::TextInputClient* client) override;
-  void OnFocus() override;
-  void OnBlur() override;
-  void OnCaretBoundsChanged(const ui::TextInputClient* client) override;
-  void OnTextInputStateChanged(const ui::TextInputClient* text_client) override;
-  void OnInputMethodDestroyed(const ui::InputMethod* input_method) override;
-  void OnShowImeIfNeeded() override;
-
-  TextInputTypeObserverPtr text_input_type_observer_;
-  mojo::Binding<KeyboardUIHandlerMojo> binding_;
-
-  DISALLOW_COPY_AND_ASSIGN(VKMojoHandler);
-};
-
-}  // namespace keyboard
-
-#endif  // UI_KEYBOARD_WEBUI_VK_MOJO_HANDLER_H_