Run input_method_bridge_unittest on Mac, remove unused DummyInputMethodDelegate

ui/base/ime/dummy_input_method_delegate.h

-// Copyright 2013 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_BASE_IME_DUMMY_INPUT_METHOD_DELEGATE_H_
-#define UI_BASE_IME_DUMMY_INPUT_METHOD_DELEGATE_H_
-
-#include "base/compiler_specific.h"
-#include "base/macros.h"
-#include "ui/base/ime/input_method_delegate.h"
-
-namespace ui {
-namespace internal {
-
-class UI_BASE_IME_EXPORT DummyInputMethodDelegate : public InputMethodDelegate {
- public:
-  DummyInputMethodDelegate();
-  ~DummyInputMethodDelegate() override;
-
-  // Overridden from InputMethodDelegate:
-  bool DispatchKeyEventPostIME(const ui::KeyEvent& key_event) override;
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(DummyInputMethodDelegate);
-};
-
-}  // namespace internal
-}  // namespace ui
-
-#endif  // UI_BASE_IME_DUMMY_INPUT_METHOD_DELEGATE_H_