Reland of [VSync Queue] Plug touch ack to gesture events and flush vsync queue if necessary

ui/events/gesture_event_details.h

Index: ui/events/gesture_event_details.h
diff --git a/ui/events/gesture_event_details.h b/ui/events/gesture_event_details.h
index 2b066d56188c5a7ae999492165d8e74b81b8734f..907a940ead868748be92cd5c062abe0fc440ab30 100644
--- a/ui/events/gesture_event_details.h
+++ b/ui/events/gesture_event_details.h
@@ -43,6 +43,15 @@
   GestureDeviceType device_type() const { return device_type_; }
   void set_device_type(GestureDeviceType device_type) {
     device_type_ = device_type;
+  }
+
+  bool is_source_touch_event_set_non_blocking() const {
+    return is_source_touch_event_set_non_blocking_;
+  }
+  void set_is_source_touch_event_set_non_blocking(
+      bool is_source_touch_event_set_non_blocking) {
+    is_source_touch_event_set_non_blocking_ =
+        is_source_touch_event_set_non_blocking;
   }
 
   int touch_points() const { return touch_points_; }
@@ -225,6 +234,8 @@
 
   GestureDeviceType device_type_;
 
+  bool is_source_touch_event_set_non_blocking_ = false;
+
   int touch_points_;  // Number of active touch points in the gesture.
 
   // Bounding box is an axis-aligned rectangle that contains all the