Wire up gesturetap in SkyShell

sky/services/viewport/input_event.mojom

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 module sky;
 
 enum EventType {
   UNKNOWN,
+  POINTER_CANCEL,
   POINTER_DOWN,
+  POINTER_MOVE,
   POINTER_UP,
-  POINTER_MOVE,
-  POINTER_CANCEL,
+  GESTURE_FLING_CANCEL,
+  GESTURE_FLING_START,
+  GESTURE_LONG_PRESS,
   GESTURE_SCROLL_BEGIN,
+  GESTURE_SCROLL_END,
   GESTURE_SCROLL_UPDATE,
-  GESTURE_SCROLL_END,
-  GESTURE_FLING_START,
-  GESTURE_FLING_CANCEL,
+  GESTURE_SHOW_PRESS,
+  GESTURE_TAP,
+  GESTURE_TAP_DOWN,
 };
 
 enum PointerKind {
   TOUCH,
 };
 
 struct PointerData {
   int32 pointer;
   PointerKind kind;
   float x;
   float y;
   int32 buttons;
   float pressure;
   float pressure_min;
   float pressure_max;
   float distance;
   float distance_min;
   float distance_max;
   float radius_major;
   float radius_minor;
   float radius_min;
   float radius_max;
   float orientation;
   float tilt;
 };
 
 struct GestureData {
-    float x;
-    float y;
-    float dx;
-    float dy;
-    float velocityX;
-    float velocityY;
+  float x;
+  float y;
+  float dx;
+  float dy;
+  float velocityX;
+  float velocityY;
 };
 
 struct InputEvent {
   EventType type;
   int64 time_stamp;
   PointerData? pointer_data;
   GestureData? gesture_data;
 };