Make event-targeting asynchronous in window server.

services/ui/ws/window_server.cc

Index: services/ui/ws/window_server.cc
diff --git a/services/ui/ws/window_server.cc b/services/ui/ws/window_server.cc
index 50ed7c452b2d7d8b592622873dc165421f9fb8c8..5bc9cd0cf08ae183b19f97f0c0c045bffb156733 100644
--- a/services/ui/ws/window_server.cc
+++ b/services/ui/ws/window_server.cc
@@ -69,7 +69,8 @@ WindowServer::WindowServer(WindowServerDelegate* delegate)
       next_wm_change_id_(0),
       gpu_host_(new GpuHost(this)),
       window_manager_window_tree_factory_set_(this, &user_id_tracker_),
-      frame_sink_manager_client_binding_(this) {
+      frame_sink_manager_client_binding_(this),
+      weak_ptr_factory_(this) {
   user_id_tracker_.AddObserver(this);
   OnUserIdAdded(user_id_tracker_.active_id());
   gpu_host_->CreateFrameSinkManager(
@@ -598,9 +599,9 @@ void WindowServer::UpdateNativeCursorFromMouseLocation(ServerWindow* window) {
   if (display_root) {
     EventDispatcher* event_dispatcher =
         display_root->window_manager_state()->event_dispatcher();
-    event_dispatcher->UpdateCursorProviderByLastKnownLocation();
-    display_root->display()->UpdateNativeCursor(
-        event_dispatcher->GetCurrentMouseCursor());
+    event_dispatcher->UpdateCursorProviderByLastKnownLocation(
+        base::Bind(&WindowServer::OnCursorUpdated,
+                   weak_ptr_factory_.GetWeakPtr(), display_root));

[sky, 2017/05/15 21:20:23]

In this code you shouldn't need a weakptrfactory as WindowServer owns everything
and will outlive the eventdispatcher.

[riajiang, 2017/05/17 02:01:59]

Ah I see. And deleted this since not passing a callback anymore.

   }
 }
 
@@ -615,9 +616,16 @@ void WindowServer::UpdateNativeCursorIfOver(ServerWindow* window) {
   if (window != event_dispatcher->GetWindowForMouseCursor())
     return;
 
-  event_dispatcher->UpdateNonClientAreaForCurrentWindow();
+  event_dispatcher->UpdateNonClientAreaForCurrentWindow(
+      base::Bind(&WindowServer::OnCursorUpdated, weak_ptr_factory_.GetWeakPtr(),
+                 display_root));
+}
+
+void WindowServer::OnCursorUpdated(WindowManagerDisplayRoot* display_root) {

[sky, 2017/05/15 21:20:24]

Style guide says position of declaration and defintion should match.

   display_root->display()->UpdateNativeCursor(
-      event_dispatcher->GetCurrentMouseCursor());
+      display_root->window_manager_state()
+          ->event_dispatcher()
+          ->GetCurrentMouseCursor());
 }
 
 bool WindowServer::IsUserInHighContrastMode(const UserId& user) const {