mus: Server-side implementation of modal windows

components/mus/ws/connection_manager.cc

Index: components/mus/ws/connection_manager.cc
diff --git a/components/mus/ws/connection_manager.cc b/components/mus/ws/connection_manager.cc
index 47c896a9a1923277a1300105f6930d4188a88dfe..cdd8a4616b6e32f8533333c44acfb0ae5efba98d 100644
--- a/components/mus/ws/connection_manager.cc
+++ b/components/mus/ws/connection_manager.cc
@@ -675,6 +675,20 @@ void ConnectionManager::OnWillChangeWindowVisibility(ServerWindow* window) {
   }
 }
 
+void ConnectionManager::OnWindowVisibilityChanged(ServerWindow* window) {
+  if (!window->is_modal() || !window->IsDrawn())
+    return;
+
+  WindowTreeHostImpl* host = GetWindowTreeHostByWindow(window);
+  ServerWindow* capture_window = host->GetCaptureWindow();
+  if (window->transient_parent() &&
+      !window->transient_parent()->Contains(capture_window)) {
+    return;
+  }
+
+  host->SetCapture(nullptr, false);
+}
+
 void ConnectionManager::OnWindowPredefinedCursorChanged(ServerWindow* window,
                                                         int32_t cursor_id) {
   if (in_destructor_)