cc: Post the missed BeginFrame to a new stack

cc/test/test_delegating_output_surface.cc

Index: cc/test/test_delegating_output_surface.cc
diff --git a/cc/test/test_delegating_output_surface.cc b/cc/test/test_delegating_output_surface.cc
index 64a15fde20b2342dd5d5784f86ef0d09b8a96123..9536801436b91ffde8d164f3a00a788dd9bc5afb 100644
--- a/cc/test/test_delegating_output_surface.cc
+++ b/cc/test/test_delegating_output_surface.cc
@@ -110,17 +110,28 @@ void TestDelegatingOutputSurface::SwapBuffers(CompositorFrame frame) {
       frame.delegated_frame_data->render_pass_list.back()->output_rect.size();
   display_->Resize(frame_size);
 
+  bool synchronous = !display_->has_scheduler();
+
   surface_factory_->SubmitCompositorFrame(
       delegated_surface_id_, std::move(frame),
       base::Bind(&TestDelegatingOutputSurface::DrawCallback,
-                 weak_ptrs_.GetWeakPtr()));
+                 weak_ptrs_.GetWeakPtr(), synchronous));
 
   if (!display_->has_scheduler())
     display_->DrawAndSwap();
 }
 
-void TestDelegatingOutputSurface::DrawCallback() {
-  client_->DidSwapBuffersComplete();
+void TestDelegatingOutputSurface::DrawCallback(bool synchronous) {
+  // This is the frame ack to unthrottle the next frame, not actually a notice
+  // that drawing is done.
+  if (synchronous) {
+    // For synchronous draws, this must be posted to a new stack because we are
+    // still the original call to SwapBuffers, and we want to leave that before
+    // saying that it is done.
+    OutputSurface::PostSwapBuffersComplete();
+  } else {
+    client_->DidSwapBuffersComplete();
+  }
 }
 
 void TestDelegatingOutputSurface::ForceReclaimResources() {