Don't pass touches to gesture recognizer for async acks.

ui/aura/test/aura_test_utils.cc

Index: ui/aura/test/aura_test_utils.cc
diff --git a/ui/aura/test/aura_test_utils.cc b/ui/aura/test/aura_test_utils.cc
index fe4120b4dcddc9a8f25e9d37b54f7dea32bc694f..f7b00276ae4c092e45ad387b8f82e7cb5bfff4c1 100644
--- a/ui/aura/test/aura_test_utils.cc
+++ b/ui/aura/test/aura_test_utils.cc
@@ -17,6 +17,10 @@ class WindowTreeHostTestApi {
     return host_->last_cursor_request_position_in_host_;
   }
 
+  void set_dispatcher(WindowEventDispatcher* dispatcher) {
+    host_->dispatcher_.reset(dispatcher);
+  }
+
  private:
   WindowTreeHost* host_;
 
@@ -28,5 +32,11 @@ const gfx::Point& QueryLatestMousePositionRequestInHost(WindowTreeHost* host) {
   return host_test_api.last_cursor_request_position_in_host();
 }
 
+void SetHostDispatcher(WindowTreeHost* host,
+                       WindowEventDispatcher* dispatcher) {
+  WindowTreeHostTestApi host_test_api(host);
+  host_test_api.set_dispatcher(dispatcher);
+}
+
 }  // namespace test
 }  // namespace aura