Fixes bug in ServerWindowCompositorFrameSinkManager

services/ui/ws/server_window.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 SERVICES_UI_WS_SERVER_WINDOW_H_
 #define SERVICES_UI_WS_SERVER_WINDOW_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 88 matching lines @@
   void SetCanAcceptDrops(bool accepts_drags);
 
   ui::mojom::Cursor cursor() const { return cursor_id_; }
   ui::mojom::Cursor non_client_cursor() const {
     return non_client_cursor_id_;
   }
 
   const ServerWindow* parent() const { return parent_; }
   ServerWindow* parent() { return parent_; }
 
+  // NOTE: this returns null if the window does not have an ancestor associated
+  // with a display.
   const ServerWindow* GetRoot() const;
   ServerWindow* GetRoot() {
     return const_cast<ServerWindow*>(
         const_cast<const ServerWindow*>(this)->GetRoot());
   }
 
   const Windows& children() const { return children_; }
 
   // Returns the ServerWindow object with the provided |id| if it lies in a
   // subtree of |this|.
@@ skipping 80 matching lines @@
 #if !defined(NDEBUG) || defined(DCHECK_ALWAYS_ON)
   std::string GetDebugWindowHierarchy() const;
   std::string GetDebugWindowInfo() const;
   void BuildDebugInfo(const std::string& depth, std::string* result) const;
 #endif
 
  private:
   // Implementation of removing a window. Doesn't send any notification.
   void RemoveImpl(ServerWindow* window);
 
+  // Called when the root window changes from |old_root| to |new_root|. This is
+  // called after the window is moved from |old_root| to |new_root|.
+  void ProcessRootChanged(ServerWindow* old_root, ServerWindow* new_root);
+
   // Called when this window's stacking order among its siblings is changed.
   void OnStackingChanged();
 
   static void ReorderImpl(ServerWindow* window,
                           ServerWindow* relative,
                           mojom::OrderDirection diretion);
 
   // Returns a pointer to the stacking target that can be used by
   // RestackTransientDescendants.
   static ServerWindow** GetStackingTarget(ServerWindow* window);
@@ skipping 43 matching lines @@
 
   base::ObserverList<ServerWindowObserver> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(ServerWindow);
 };
 
 }  // namespace ws
 }  // namespace ui
 
 #endif  // SERVICES_UI_WS_SERVER_WINDOW_H_