diff --git a/content/browser/renderer_host/render_frame_host_impl.cc b/content/browser/renderer_host/render_frame_host_impl.cc
--- a/content/browser/renderer_host/render_frame_host_impl.cc
+++ b/content/browser/renderer_host/render_frame_host_impl.cc
@@ -7,6 +7,7 @@

 #include <memory>

+#include "base/run_loop.h"
 #include "base/callback_helpers.h"
 #include "base/command_line.h"
 #include "base/containers/contains.h"
@@ -9323,6 +9324,14 @@ void RenderFrameHostImpl::ExitFullscreen() {
   base::RecordAction(base::UserMetricsAction("ExitFullscreen_API"));
   delegate_->ExitFullscreenMode(/*will_cause_resize=*/true);

+  // PoC: Pump tasks to allow pending RFHI destruction to process.
+  // Simulates the race window from ::SetWindowPos nested message loop.
+  {
+    base::RunLoop run_loop(base::RunLoop::Type::kNestableTasksAllowed);
+    base::SingleThreadTaskRunner::GetCurrentDefault()->PostDelayedTask(
+        FROM_HERE, run_loop.QuitClosure(), base::Milliseconds(500));
+    run_loop.Run();
+  }
+
   // The previous call might change the fullscreen state. We need to make sure
   // the renderer is aware of that, which is done via the resize message.