Changes how window manager obtains WindowTree from mus

components/mus/ws/window_tree.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 COMPONENTS_MUS_WS_WINDOW_TREE_H_
 #define COMPONENTS_MUS_WS_WINDOW_TREE_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 111 matching lines @@
         const_cast<const WindowTree*>(this)->GetDisplay(window));
   }
 
   const WindowManagerState* GetWindowManagerState(
       const ServerWindow* window) const;
   WindowManagerState* GetWindowManagerState(const ServerWindow* window) {
     return const_cast<WindowManagerState*>(
         const_cast<const WindowTree*>(this)->GetWindowManagerState(window));
   }
 
+  // Adds a new root to this tree. This is only valid for window managers.
+  void AddRootForWindowManager(const ServerWindow* root);
+
   // Invoked when a tree is about to be destroyed.
   void OnWindowDestroyingTreeImpl(WindowTree* tree);
 
   // These functions are synchronous variants of those defined in the mojom. The
   // WindowTree implementations all call into these. See the mojom for details.
   bool SetCapture(const ClientWindowId& client_window_id);
   bool NewWindow(const ClientWindowId& client_window_id,
                  const std::map<std::string, std::vector<uint8_t>>& properties);
   bool AddWindow(const ClientWindowId& parent_id,
                  const ClientWindowId& child_id);
@@ skipping 97 matching lines @@
     DELETED,
 
     // Another client is being embedded in the window.
     EMBED,
   };
 
   DisplayManager* display_manager();
   const DisplayManager* display_manager() const;
 
   // Used when this tree is the window manager.
-  Display* GetDisplayForWindowManager();
   WindowManagerState* GetWindowManagerStateForWindowManager();
 
   bool ShouldRouteToWindowManager(const ServerWindow* window) const;
 
   ClientWindowId ClientWindowIdForWindow(const ServerWindow* window) const;
 
   // Returns true if |id| is a valid WindowId for a new window.
   bool IsValidIdForNewWindow(const ClientWindowId& id) const;
 
   WindowId GenerateNewWindowId();
@@ skipping 211 matching lines @@
   std::unique_ptr<WaitingForTopLevelWindowInfo>
       waiting_for_top_level_window_info_;
 
   DISALLOW_COPY_AND_ASSIGN(WindowTree);
 };
 
 }  // namespace ws
 }  // namespace mus
 
 #endif  // COMPONENTS_MUS_WS_WINDOW_TREE_H_