IME for Mus: Use ui::InputMethodChromeOS to provide logic for ime driver.

chrome/browser/ui/views/ime_driver/simple_input_method.cc

+// Copyright 2016 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 "chrome/browser/ui/views/ime_driver/simple_input_method.h"
+
+SimpleInputMethod::SimpleInputMethod() {}
+
+SimpleInputMethod::~SimpleInputMethod() {}
+
+void SimpleInputMethod::OnTextInputModeChanged(
+    ui::mojom::TextInputMode text_input_mode) {}
+
+void SimpleInputMethod::OnTextInputTypeChanged(
+    ui::mojom::TextInputType text_input_type) {}
+
+void SimpleInputMethod::OnCaretBoundsChanged(const gfx::Rect& caret_bounds) {}
+
+void SimpleInputMethod::ProcessKeyEvent(
+    std::unique_ptr<ui::Event> key_event,
+    const ProcessKeyEventCallback& callback) {
+  callback.Run(false);
+}
+
+void SimpleInputMethod::CancelComposition() {}