Remove Widget::OnRootViewLayout().

ui/views/mus/desktop_window_tree_host_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 "ui/views/mus/desktop_window_tree_host_mus.h"
 
 #include "base/memory/ptr_util.h"
 #include "ui/aura/client/aura_constants.h"
 #include "ui/aura/client/drag_drop_client.h"
 #include "ui/aura/client/focus_client.h"
@@ skipping 378 matching lines @@
 }
 
 void DesktopWindowTreeHostMus::InitModalType(ui::ModalType modal_type) {
   window()->SetProperty(aura::client::kModalKey, modal_type);
 }
 
 void DesktopWindowTreeHostMus::FlashFrame(bool flash_frame) {
   window()->SetProperty(aura::client::kDrawAttentionKey, flash_frame);
 }
 
-void DesktopWindowTreeHostMus::OnRootViewLayout() {}
-
 bool DesktopWindowTreeHostMus::IsAnimatingClosed() const {
   return false;
 }
 
 bool DesktopWindowTreeHostMus::IsTranslucentWindowOpacitySupported() const {
   return true;
 }
 
 void DesktopWindowTreeHostMus::SizeConstraintsChanged() {
   Widget* widget = native_widget_delegate_->AsWidget();
@@ skipping 41 matching lines @@
   if (window == this->window()) {
     is_active_ = true;
     desktop_native_widget_aura_->HandleActivationChanged(true);
   } else if (is_active_) {
     is_active_ = false;
     desktop_native_widget_aura_->HandleActivationChanged(false);
   }
 }
 
 }  // namespace views