Implement aura::WindowPortMus::CreateCompositorFrameSink()

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 838 matching lines @@
     display->platform_display()->GetFrameGenerator()->OnSurfaceCreated(
         surface_info);
     display->root_window()
         ->GetOrCreateCompositorFrameSinkManager()
         ->ClaimTemporaryReference(surface_info.id());
     return;
   }
 
   HandleTemporaryReferenceForNewSurface(surface_info.id(), window);
 
-  if (!window->parent())
-    return;
-
-  WindowTree* window_tree = GetTreeWithId(window->parent()->id().client_id);
+  // We always use the client_id of window's id (even for embedded window),

[sky, 2017/05/26 23:14:18]

How about, 'We always use the owner of the window...'

[Peng, 2017/05/30 19:46:27]

Done.

+  // because an embedded window's id is allocated by the parent's window tree.
+  WindowTree* window_tree = GetTreeWithId(window->id().client_id);
   if (window_tree)
     window_tree->ProcessWindowSurfaceChanged(window, surface_info);
 }
 
 void WindowServer::OnActiveUserIdChanged(const UserId& previously_active_id,
                                          const UserId& active_id) {
 }
 
 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