New flingCancel flag to prevent fling boosting.

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 450 matching lines @@
             // instead of a bool.
             int preventPropagation;
         } scrollUpdate;
 
         struct {
             float velocityX;
             float velocityY;
         } flingStart;
 
         struct {
+            // Don't treat flingCancel as a part of fling boost

[Rick Byers, 2014/12/10 19:01:01]

Nit: Add "if true" since we don't want to imply that most flingCancel events
will have this set.

+            // events sequence.
+            bool preventBoosting;
+        } flingCancel;
+
+        struct {
             float scale;
         } pinchUpdate;
     } data;
 
     WebGestureEvent()
         : WebInputEvent(sizeof(WebGestureEvent))
         , x(0)
         , y(0)
         , globalX(0)
         , globalY(0)
@@ skipping 34 matching lines @@
         , causesScrollingIfUncanceled(false)
     {
     }
 };
 
 #pragma pack(pop)
 
 } // namespace blink
 
 #endif