Delay Input.dispatchKeyEvent response until after key event ack.

content/public/test/browser_test_utils.cc

Index: content/public/test/browser_test_utils.cc
diff --git a/content/public/test/browser_test_utils.cc b/content/public/test/browser_test_utils.cc
index 7d066fe1efd414f6abb311af94bc09f107b83b1d..2e4efe958ce7d79488f31bf7851cbefa8177f7ba 100644
--- a/content/public/test/browser_test_utils.cc
+++ b/content/public/test/browser_test_utils.cc
@@ -1527,9 +1527,13 @@ bool InputMsgWatcher::OnMessageReceived(const IPC::Message& message) {
   return false;
 }
 
+bool InputMsgWatcher::HasReceivedAck() const {
+  return ack_result_ != INPUT_EVENT_ACK_STATE_UNKNOWN;
+}
+
 uint32_t InputMsgWatcher::WaitForAck() {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
-  if (ack_result_ != INPUT_EVENT_ACK_STATE_UNKNOWN)
+  if (HasReceivedAck())
     return ack_result_;
   base::RunLoop run_loop;
   base::AutoReset<base::Closure> reset_quit(&quit_, run_loop.QuitClosure());