IME for Mus: Remove OnTextInputModeChanged() from IME's mojo API.

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::TextInputMode text_input_mode) {}
-
 void SimpleInputMethod::OnTextInputTypeChanged(
     ui::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() {}