Refactor backdrop that is currently used in the maximized mode.

components/exo/wm_helper_mus.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 "components/exo/wm_helper_mus.h"
 
 #include "ui/aura/client/focus_client.h"
 #include "ui/aura/env.h"
 #include "ui/aura/mus/focus_synchronizer.h"
 #include "ui/aura/mus/window_tree_client.h"
@@ skipping 68 matching lines @@
 
 void WMHelperMus::RemovePostTargetHandler(ui::EventHandler* handler) {
   aura::Env::GetInstance()->RemovePostTargetHandler(handler);
 }
 
 bool WMHelperMus::IsMaximizeModeWindowManagerEnabled() const {
   NOTIMPLEMENTED();
   return false;
 }
 
-bool WMHelperMus::IsSpokenFeedbackEnabled() const {
-  NOTIMPLEMENTED();
-  return false;
-}
-
-void WMHelperMus::PlayEarcon(int sound_key) const {
-  NOTIMPLEMENTED();
-}
-
 void WMHelperMus::OnActiveFocusClientChanged(
     aura::client::FocusClient* focus_client,
     aura::Window* focus_client_root) {
   SetActiveFocusClient(focus_client, focus_client_root);
 }
 
 void WMHelperMus::OnWindowFocused(aura::Window* gained_focus,
                                   aura::Window* lost_focus) {
   if (focused_window_ == gained_focus)
     return;
@@ skipping 40 matching lines @@
   NotifyWindowFocused(focused_window_, lost_focus);
 }
 
 aura::client::ActivationClient* WMHelperMus::GetActivationClient() {
   return root_with_active_focus_client_
              ? aura::client::GetActivationClient(root_with_active_focus_client_)
              : nullptr;
 }
 
 }  // namespace exo