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;
+  ClientSpecificId window_tree_id = window->id().client_id;
+  // If the window has a parent, we should use the parent's tree, because the
+  // window could be an embedded window, and the window will be in both
+  // the embedder's tree and embeddee's tree, in this case we shold notify
+  // the embedder's tree about the surface change.
+  if (window->parent())
+    window_tree_id = window->parent()->id().client_id;

[Fady Samuel, 2017/05/25 20:58:03]

So we agreed to undo this change?

[Peng, 2017/05/25 23:10:39]

The origin code will not send the new surface id to the window tree client, if
the window is not parented. We need this change, so the client can know the
surface id, and use it later.

[Peng, 2017/05/26 13:58:25]

I just realized, we should never use the parent window's client id. 

It is because, for an embedded window, the window's id is always allocated
within parent window tree, so we should just use the window's client id.

But for a "local window"'s parent is an embedded window, we cannot use parent
window's client id. It will notify a wrong tree.

 
-  WindowTree* window_tree = GetTreeWithId(window->parent()->id().client_id);
+  WindowTree* window_tree = GetTreeWithId(window_tree_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