mus: Server-side implementation of modal windows

components/mus/ws/display.cc

Index: components/mus/ws/display.cc
diff --git a/components/mus/ws/display.cc b/components/mus/ws/display.cc
index ef878ead97ca64be53fc4cd3dd92951f8f1fb127..410a8359547a01a60fcc01fa3901ccf4983e8eb3 100644
--- a/components/mus/ws/display.cc
+++ b/components/mus/ws/display.cc
@@ -213,11 +213,24 @@ const WindowManagerState* Display::GetWindowManagerStateForUser(
   return iter == window_manager_state_map_.end() ? nullptr : iter->second.get();
 }
 
-void Display::SetCapture(ServerWindow* window, bool in_nonclient_area) {
+bool Display::SetCapture(ServerWindow* window, bool in_nonclient_area) {
   ServerWindow* capture_window = event_dispatcher_.capture_window();
   if (capture_window == window)
+    return true;
+  return event_dispatcher_.SetCaptureWindow(window, in_nonclient_area);
+}
+
+void Display::ReleaseCaptureForModalWindow(ServerWindow* window) {
+  if (!window->is_modal() || !window->IsDrawn())
+    return;
+
+  ServerWindow* capture_window = GetCaptureWindow();
+  if (window->transient_parent() &&
+      !window->transient_parent()->Contains(capture_window)) {
     return;
-  event_dispatcher_.SetCaptureWindow(window, in_nonclient_area);
+  }
+
+  SetCapture(nullptr, false);
 }
 
 mojom::Rotation Display::GetRotation() const {