Register the window in MaximizeModeWindowManager when the window is shown.

ash/common/wm/maximize_mode/maximize_mode_window_manager.h

 // Copyright 2014 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 ASH_COMMON_WM_MAXIMIZE_MODE_MAXIMIZE_MODE_WINDOW_MANAGER_H_
 #define ASH_COMMON_WM_MAXIMIZE_MODE_MAXIMIZE_MODE_WINDOW_MANAGER_H_
 
 #include <stdint.h>
 
 #include <map>
-#include <set>
+#include <unordered_set>
 
 #include "ash/ash_export.h"
 #include "ash/common/shell_observer.h"
 #include "ash/common/wm/window_state.h"
 #include "ash/common/wm_window_observer.h"
 #include "base/macros.h"
 #include "ui/display/display_observer.h"
 
 namespace ash {
 class MaximizeModeController;
@@ skipping 34 matching lines @@
 
   // Overridden from WindowObserver:
   void OnWindowDestroying(WmWindow* window) override;
   void OnWindowTreeChanged(WmWindow* window,
                            const TreeChangeParams& params) override;
   void OnWindowPropertyChanged(WmWindow* window,
                                WmWindowProperty window_property) override;
   void OnWindowBoundsChanged(WmWindow* window,
                              const gfx::Rect& old_bounds,
                              const gfx::Rect& new_bounds) override;
+  void OnWindowVisibilityChanging(WmWindow* window, bool visible) override;
 
   // display::DisplayObserver overrides:
   void OnDisplayAdded(const display::Display& display) override;
   void OnDisplayRemoved(const display::Display& display) override;
   void OnDisplayMetricsChanged(const display::Display& display,
                                uint32_t metrics) override;
 
  protected:
   friend class MaximizeModeController;
 
@@ skipping 39 matching lines @@
   // Returns true when the |window| is a container window.
   bool IsContainerWindow(WmWindow* window);
 
   // Add a backdrop behind the currently active window on each desktop.
   void EnableBackdropBehindTopWindowOnEachDisplay(bool enable);
 
   // Every window which got touched by our window manager gets added here.
   WindowToState window_state_map_;
 
   // All container windows which have to be tracked.
-  std::set<WmWindow*> observed_container_windows_;
+  std::unordered_set<WmWindow*> observed_container_windows_;
+
+  // Windows added to the container, but not yet shown.
+  std::unordered_set<WmWindow*> added_windows_;
 
   // True if all backdrops are hidden.
   bool backdrops_hidden_;
 
   std::unique_ptr<wm::MaximizeModeEventHandler> event_handler_;
 
   DISALLOW_COPY_AND_ASSIGN(MaximizeModeWindowManager);
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_WM_MAXIMIZE_MODE_MAXIMIZE_MODE_WINDOW_MANAGER_H_