Revert of mus: Enable system modal windows

components/mus/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 COMPONENTS_MUS_WS_SERVER_WINDOW_H_
 #define COMPONENTS_MUS_WS_SERVER_WINDOW_H_
 
 #include <stdint.h>
 
 #include <vector>
@@ skipping 82 matching lines @@
 
   std::vector<const ServerWindow*> GetChildren() const;
   std::vector<ServerWindow*> GetChildren();
   const Windows& children() const { return children_; }
 
   // Returns the ServerWindow object with the provided |id| if it lies in a
   // subtree of |this|.
   ServerWindow* GetChildWindow(const WindowId& id);
 
   // Transient window management.
-  // Adding transient child fails if the child window is modal to system.
-  bool AddTransientWindow(ServerWindow* child);
+  void AddTransientWindow(ServerWindow* child);
   void RemoveTransientWindow(ServerWindow* child);
 
   ServerWindow* transient_parent() { return transient_parent_; }
   const ServerWindow* transient_parent() const { return transient_parent_; }
 
   const Windows& transient_children() const { return transient_children_; }
 
   bool is_modal() const { return is_modal_; }
   void SetModal();
 
+  bool IsBlockedByModalWindow() const;
+
+  // Returns the window that events targeted to this window should be retargeted
+  // to; according to modal windows. If any modal window is blocking this
+  // window, returns the topmost one; otherwise, returns this window.
+  const ServerWindow* GetModalTarget() const;
+  ServerWindow* GetModalTarget() {
+    return const_cast<ServerWindow*>(
+        static_cast<const ServerWindow*>(this)->GetModalTarget());
+  }
+
   // Returns true if this contains |window| or is |window|.
   bool Contains(const ServerWindow* window) const;
 
   // Returns the visibility requested by this window. IsDrawn() returns whether
   // the window is actually visible on screen.
   bool visible() const { return visible_; }
   void SetVisible(bool value);
 
   float opacity() const { return opacity_; }
   void SetOpacity(float value);
@@ skipping 98 matching lines @@
 
   base::ObserverList<ServerWindowObserver> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(ServerWindow);
 };
 
 }  // namespace ws
 }  // namespace mus
 
 #endif  // COMPONENTS_MUS_WS_SERVER_WINDOW_H_