DesktopAura: Track windows "owned" via the DesktopWindowTreeHost

ui/views/mus/desktop_window_tree_host_mus.h

 // 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.
 
 #ifndef UI_VIEWS_WIDGET_DESKTOP_AURA_DESKTOP_WINDOW_TREE_HOST_MUS_H_
 #define UI_VIEWS_WIDGET_DESKTOP_AURA_DESKTOP_WINDOW_TREE_HOST_MUS_H_
 
 #include <memory>
 #include <set>
 
@@ skipping 104 matching lines @@
   void SetOpacity(float opacity) override;
   void SetWindowIcons(const gfx::ImageSkia& window_icon,
                       const gfx::ImageSkia& app_icon) override;
   void InitModalType(ui::ModalType modal_type) override;
   void FlashFrame(bool flash_frame) override;
   bool IsAnimatingClosed() const override;
   bool IsTranslucentWindowOpacitySupported() const override;
   void SizeConstraintsChanged() override;
   bool ShouldUpdateWindowTransparency() const override;
   bool ShouldUseDesktopNativeCursorManager() const override;
+  std::vector<DesktopWindowTreeHost*> GetOwnedTopLevelHosts() const override;
 
   // MusClientObserver:
   void OnWindowManagerFrameValuesChanged() override;
 
   // WidgetObserver:
   void OnWidgetActivationChanged(Widget* widget, bool active) override;
 
   // WindowTreeHostMus:
   void ShowImpl() override;
   void HideImpl() override;
@@ skipping 25 matching lines @@
 
   // Used so that Close() isn't immediate.
   base::WeakPtrFactory<DesktopWindowTreeHostMus> close_widget_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(DesktopWindowTreeHostMus);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_WIDGET_DESKTOP_AURA_DESKTOP_WINDOW_TREE_HOST_MUS_H_