mus: Unset the cursor client during teardown.

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/cursor_client.h"
 #include "ui/aura/client/drag_drop_client.h"
@@ skipping 172 matching lines @@
   // DesktopNativeWidgetAura registers the association between |content_window_|
   // and Widget, but code may also want to go from the root (window()) to the
   // Widget. This call enables that.
   NativeWidgetAura::RegisterNativeWidgetForWindow(desktop_native_widget_aura,
                                                   window());
   // TODO: use display id and bounds if available, likely need to pass in
   // InitParams for that.
 }
 
 DesktopWindowTreeHostMus::~DesktopWindowTreeHostMus() {
+  // The cursor-client can be accessed during WindowTreeHostMus tear-down. So
+  // the cursor-client needs to be unset on the root-window before
+  // |cursor_manager_| is destroyed.
+  aura::client::SetCursorClient(window(), nullptr);
   MusClient::Get()->RemoveObserver(this);
   aura::Env::GetInstance()->RemoveObserver(this);
   desktop_native_widget_aura_->OnDesktopWindowTreeHostDestroyed(this);
 }
 
 bool DesktopWindowTreeHostMus::IsDocked() const {
   return window()->GetProperty(aura::client::kShowStateKey) ==
          ui::SHOW_STATE_DOCKED;
 }
 
@@ skipping 505 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