chromeos: Makes mushrome use simplified display management

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 808 matching lines @@
     frame_sink_manager_->DropTemporaryReference(surface_info.id());
     return;
   }
 
   // This is only used for testing to observe that a window has a
   // CompositorFrame.
   if (!window_paint_callback_.is_null())
     window_paint_callback_.Run(window);
 
   auto* display = display_manager_->GetDisplayContaining(window);
-  if (display && window == display->GetActiveRootWindow()) {
+  WindowManagerDisplayRoot* display_root =
+      display ? display->GetActiveWindowManagerDisplayRoot() : nullptr;
+  if (display_root && (window == display_root->root() ||

[kylechar, 2017/04/26 16:41:44]

Can you pull some of this conditional out into other variables to simplify it?

[sky, 2017/04/26 19:36:42]

Done.

+                       (!display_root->window_manager_state()
+                             ->window_tree()
+                             ->automatically_create_display_roots() &&
+                        window->parent() == display_root->root()))) {
     // A new surface for a WindowManager root has been created. This is a
     // special case because ServerWindows created by the WindowServer are not
     // part of a WindowTree. Send the SurfaceId directly to FrameGenerator and
     // claim the temporary reference for the display root.
     display->platform_display()->GetFrameGenerator()->OnSurfaceCreated(
         surface_info);
     display->root_window()
         ->GetOrCreateCompositorFrameSinkManager()
         ->ClaimTemporaryReference(surface_info.id());
     return;
@@ skipping 16 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