use enum to specify deviceSource for fling animation

public/web/WebInputEvent.h

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 391 matching lines @@
         , canRubberbandLeft(true)
         , canRubberbandRight(true)
     {
     }
 };
 
 // WebGestureEvent --------------------------------------------------------------
 
 class WebGestureEvent : public WebInputEvent {
 public:
-    enum SourceDevice {
-        Touchpad,
-        Touchscreen,
-    };
-
     int x;
     int y;
     int globalX;
     int globalY;
-    // TODO(rjkroege): Restore typing once chromium side lands
-    // (http://crbug.com/343327)
-    int sourceDevice;
+    WebGestureDevice sourceDevice;
 
     union {
         // Tap information must be set for GestureTap, GestureTapUnconfirmed,
         // and GestureDoubleTap events.
         struct {
             int tapCount;
             float width;
             float height;
         } tap;
 
@@ skipping 85 matching lines @@
         , cancelable(true)
     {
     }
 };
 
 #pragma pack(pop)
 
 } // namespace blink
 
 #endif