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 13 matching lines @@
 #include "services/ui/ws/window_manager_state.h"
 #include "services/ui/ws/window_manager_window_tree_factory.h"
 #include "services/ui/ws/window_server_delegate.h"
 #include "services/ui/ws/window_tree.h"
 #include "services/ui/ws/window_tree_binding.h"
 #include "ui/gfx/geometry/size_conversions.h"
 
 namespace ui {
 namespace ws {
 
+namespace {
+
+// Returns true if |window| is considered the active display root of |display|.
+bool IsWindowConsideredDisplayRoot(const Display* display,

[kylechar, 2017/04/27 14:26:31]

nit: The term display root is used elsewhere for the root ServerWindow that has
a corresponding FrameGenerator. I think this would be more window manager root?

[sky, 2017/04/27 15:09:53]

Done.

+                                   const ServerWindow* window) {
+  if (!display)
+    return false;
+
+  const WindowManagerDisplayRoot* display_root =
+      display->GetActiveWindowManagerDisplayRoot();
+  if (!display_root)
+    return false;
+
+  if (window == display_root->root())
+    return true;
+
+  // If the window manager manually creates displays then there is an extra
+  // window, the window supplied via SetDisplayRoot().
+  return !display_root->window_manager_state()

[kylechar, 2017/04/27 14:26:31]

Can we remove this extra level of window hierarchy at some point?

[sky, 2017/04/27 15:09:53]

Possibly. If I get rid of the mode where mus automatically creates the roots
than I could.

+              ->window_tree()
+              ->automatically_create_display_roots() &&
+         window->parent() == display_root->root();
+}
+
+}  // namespace
+
 struct WindowServer::CurrentMoveLoopState {
   uint32_t change_id;
   ServerWindow* window;
   WindowTree* initiator;
   gfx::Rect revert_bounds;
 };
 
 struct WindowServer::CurrentDragLoopState {
   uint32_t change_id;
   ServerWindow* window;
@@ skipping 774 matching lines @@
   if (!window) {
     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()) {
+  Display* display = display_manager_->GetDisplayContaining(window);
+  if (IsWindowConsideredDisplayRoot(display, window)) {
     // 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