Move FrameSink hierarchy registration to DisplayCompositor interface

services/ui/ws/window_server.cc

 // 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.
 
 #include "services/ui/ws/window_server.h"
 
 #include <set>
 #include <string>
 
 #include "base/logging.h"
@@ skipping 620 matching lines @@
     return;
 
   WindowManagerDisplayRoot* display_root =
       display_manager_->GetWindowManagerDisplayRoot(window);
   if (display_root)
     display_root->window_manager_state()
         ->ReleaseCaptureBlockedByAnyModalWindow();
 
   ProcessWindowHierarchyChanged(window, new_parent, old_parent);
 
+  if (old_parent) {
+    display_compositor_->UnregisterFrameSinkHierarchy(
+        old_parent->frame_sink_id(), window->frame_sink_id());
+  }
+  if (new_parent) {
+    display_compositor_->RegisterFrameSinkHierarchy(new_parent->frame_sink_id(),
+                                                    window->frame_sink_id());
+  }
+
   UpdateNativeCursorFromMouseLocation(window);
 }
 
 void WindowServer::OnWindowBoundsChanged(ServerWindow* window,
                                          const gfx::Rect& old_bounds,
                                          const gfx::Rect& new_bounds) {
   if (in_destructor_)
     return;
 
   ProcessWindowBoundsChanged(window, old_bounds, new_bounds);
@@ skipping 151 matching lines @@
 void WindowServer::OnUserIdAdded(const UserId& id) {
   activity_monitor_map_[id] = base::MakeUnique<UserActivityMonitor>(nullptr);
 }
 
 void WindowServer::OnUserIdRemoved(const UserId& id) {
   activity_monitor_map_.erase(id);
 }
 
 }  // namespace ws
 }  // namespace ui