diff --git a/content/browser/web_contents/web_contents_impl.cc b/content/browser/web_contents/web_contents_impl.cc
--- a/content/browser/web_contents/web_contents_impl.cc
+++ b/content/browser/web_contents/web_contents_impl.cc
@@ -9717,6 +9717,14 @@
   ForSecurityDropFullscreen(display_id).RunAndReset();

+  // Widen race window: pump nestable tasks so pending WebContents
+  // destruction can execute. Simulates the natural race from
+  // ::SetWindowPos nested message loop on Windows.
+  {
+    base::RunLoop run_loop(base::RunLoop::Type::kNestableTasksAllowed);
+    base::SingleThreadTaskRunner::GetCurrentDefault()->PostDelayedTask(
+        FROM_HERE, run_loop.QuitClosure(), base::Milliseconds(2000));
+    run_loop.Run();
+  }
+
   delegate_->SetContentsBounds(this, bounds);
 }