AXAuraObjCache - clear focus client reference when window is destroyed

ui/views/accessibility/ax_aura_obj_cache.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 UI_VIEWS_ACCESSIBILITY_AX_AURA_OBJ_CACHE_H_
 #define UI_VIEWS_ACCESSIBILITY_AX_AURA_OBJ_CACHE_H_
 
 #include <stdint.h>
 
 #include <map>
 #include <vector>
 
 #include "base/macros.h"
 #include "ui/aura/client/focus_change_observer.h"
+#include "ui/aura/window_observer.h"
 #include "ui/views/views_export.h"
 
 namespace base {
 template <typename T> struct DefaultSingletonTraits;
 }
 
 namespace aura {
 namespace client {
 class FocusClient;
 }
 class Window;
 }  // namespace aura
 
 namespace views {
 class AXAuraObjWrapper;
 class View;
 class Widget;
 
 // A cache responsible for assigning id's to a set of interesting Aura views.
 class VIEWS_EXPORT AXAuraObjCache
-    : public aura::client::FocusChangeObserver {
+    : public aura::client::FocusChangeObserver,
+      public aura::WindowObserver {
  public:
   // Get the single instance of this class.
   static AXAuraObjCache* GetInstance();
 
   // Get or create an entry in the cache based on an Aura view.
   AXAuraObjWrapper* GetOrCreate(View* view);
   AXAuraObjWrapper* GetOrCreate(Widget* widget);
   AXAuraObjWrapper* GetOrCreate(aura::Window* window);
 
   // Gets an id given an Aura view.
@@ skipping 33 matching lines @@
 
   AXAuraObjCache();
   ~AXAuraObjCache() override;
 
   View* GetFocusedView();
 
   // aura::client::FocusChangeObserver override.
   void OnWindowFocused(aura::Window* gained_focus,
                        aura::Window* lost_focus) override;
 
+  // aura::WindowObserver override.
+  void OnWindowDestroying(aura::Window* window) override;
+
   template <typename AuraViewWrapper, typename AuraView>
   AXAuraObjWrapper* CreateInternal(
       AuraView* aura_view,
       std::map<AuraView*, int32_t>& aura_view_to_id_map);
 
   template <typename AuraView>
   int32_t GetIDInternal(
       AuraView* aura_view,
       const std::map<AuraView*, int32_t>& aura_view_to_id_map) const;
 
@@ skipping 12 matching lines @@
 
   // True immediately when entering this object's destructor.
   bool is_destroying_;
 
   DISALLOW_COPY_AND_ASSIGN(AXAuraObjCache);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_ACCESSIBILITY_AX_AURA_OBJ_CACHE_H_