Allow touch events to be uncancelable

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 495 matching lines @@
     WebTouchPoint touches[touchesLengthCap];
 
     unsigned changedTouchesLength;
     // List of all touches whose state has changed since the last WebTouchEvent
     WebTouchPoint changedTouches[touchesLengthCap];
 
     unsigned targetTouchesLength;
     // List of all touches which are currently down and are targeting the event recipient.
     WebTouchPoint targetTouches[touchesLengthCap];
 
+    // Whether the event can be canceled (with preventDefault). If true then the browser
+    // must wait for an ACK for this event. If false then no ACK IPC is expected.
+    // See comment at the top for why an int is used here instead of a bool.
+    int cancelable;
+
     WebTouchEvent()
         : WebInputEvent(sizeof(WebTouchEvent))
         , touchesLength(0)
         , changedTouchesLength(0)
         , targetTouchesLength(0)
+        , cancelable(true)
     {
     }
 };
 
 #pragma pack(pop)
 
 } // namespace blink
 
 #endif