[VSync Queue] Flush input in CommitComplete()

ui/events/blink/input_handler_proxy.cc

Index: ui/events/blink/input_handler_proxy.cc
diff --git a/ui/events/blink/input_handler_proxy.cc b/ui/events/blink/input_handler_proxy.cc
index 911147a1f3711d6f2c3194c06dbe65a532754199..ab90172c31bc3f7eed77bfdbc32af1c9fd182ef4 100644
--- a/ui/events/blink/input_handler_proxy.cc
+++ b/ui/events/blink/input_handler_proxy.cc
@@ -325,6 +325,14 @@ void InputHandlerProxy::HandleInputEventWithLatencyInfo(
     bool needs_animate_input = compositor_event_queue_->empty();
     compositor_event_queue_->Queue(std::move(event_with_callback),
                                    tick_clock_->NowTicks());
+
+    if (input_handler_->GetInputHandlerState() ==
+        cc::InputHandler::InputHandlerState::IDLE) {
+      // Dispatch immediately to avoid checkerboard in high latency mode.
+      DispatchQueuedInputEvents();
+      return;
+    }
+
     if (needs_animate_input)
       input_handler_->SetNeedsAnimateInput();
     return;