Centralizes more shared code between ash and mash

ash/aura/wm_window_aura.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 "ash/aura/wm_window_aura.h"
 
 #include "ash/aura/aura_layout_manager_adapter.h"
 #include "ash/aura/wm_root_window_controller_aura.h"
 #include "ash/aura/wm_shell_aura.h"
 #include "ash/common/ash_constants.h"
@@ skipping 357 matching lines @@
 void WmWindowAura::SetParentUsingContext(WmWindow* context,
                                          const gfx::Rect& screen_bounds) {
   aura::client::ParentWindowWithContext(window_, GetAuraWindow(context),
                                         screen_bounds);
 }
 
 void WmWindowAura::AddChild(WmWindow* window) {
   window_->AddChild(GetAuraWindow(window));
 }
 
+void WmWindowAura::RemoveChild(WmWindow* child) {
+  window_->RemoveChild(GetAuraWindow(child));
+}
+
 const WmWindow* WmWindowAura::GetParent() const {
   return Get(window_->parent());
 }
 
 const WmWindow* WmWindowAura::GetTransientParent() const {
   return Get(::wm::GetTransientParent(window_));
 }
 
 std::vector<WmWindow*> WmWindowAura::GetTransientChildren() {
   return FromAuraWindows(::wm::GetTransientChildren(window_));
@@ skipping 485 matching lines @@
                     OnTransientChildAdded(this, Get(transient)));
 }
 
 void WmWindowAura::OnTransientChildRemoved(aura::Window* window,
                                            aura::Window* transient) {
   FOR_EACH_OBSERVER(WmTransientWindowObserver, transient_observers_,
                     OnTransientChildRemoved(this, Get(transient)));
 }
 
 }  // namespace ash