mus: Changes SetDisplayRoot() to create actual display

services/ui/ws/window_manager_window_tree_factory.cc

Index: services/ui/ws/window_manager_window_tree_factory.cc
diff --git a/services/ui/ws/window_manager_window_tree_factory.cc b/services/ui/ws/window_manager_window_tree_factory.cc
index 0f9589b8176fa4dd47c6dd47b43877c19845f420..89711f2de86f19de85353f30fde2af3c09f8d1d5 100644
--- a/services/ui/ws/window_manager_window_tree_factory.cc
+++ b/services/ui/ws/window_manager_window_tree_factory.cc
@@ -7,6 +7,7 @@
 #include "base/bind.h"
 #include "services/ui/ws/window_manager_window_tree_factory_set.h"
 #include "services/ui/ws/window_server.h"
+#include "services/ui/ws/window_server_delegate.h"
 #include "services/ui/ws/window_tree.h"
 
 namespace ui {
@@ -38,6 +39,10 @@ void WindowManagerWindowTreeFactory::CreateWindowTree(
   if (binding_.is_bound())
     binding_.Close();
 
+  window_manager_window_tree_factory_set_->window_server()
+      ->delegate()
+      ->OnWillCreateTreeForWindowManager(automatically_create_display_roots);

[kylechar, 2017/04/19 18:06:08]

Will this work with multiple connected WMs? I know we don't actually do that,
but I think some of the tests might pretend there are multiple WMs.

[sky, 2017/04/19 19:30:03]

You are correct it would be problematic to have multiple wms connect with
different values. Service::OnWillCreateTreeForWindowManager() ignores the second
call. Will have to think what the right long term solution will be for multiple
wms. One easy solution is do away the boolean and only support the new config.

[kylechar, 2017/04/19 19:47:09]

Ah, right it ignores it. Gotcha.

+
   SetWindowTree(GetWindowServer()->CreateTreeForWindowManager(
       user_id_, std::move(window_tree_request), std::move(window_tree_client),
       automatically_create_display_roots));