Redefined the bit WebTouchEvent.causesScrollingIfUncanceled.

third_party/WebKit/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 564 matching lines @@
     enum { touchesLengthCap = 16 };
 
     unsigned touchesLength;
     // List of all touches, regardless of state.
     WebTouchPoint touches[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.
     bool cancelable;
 
-    // Whether the event will produce scroll-inducing events if uncanceled. This
-    // will be true for touchmove events after the platform slop region has been
-    // exceeded and fling-generating touchend events. Note that this doesn't
-    // necessarily mean content will scroll, only that scroll events will be
-    // generated.
-    bool causesScrollingIfUncanceled;
+    // True for touchmove events after the platform slop region has been exceeded and
+    // fling-generating touchend events.

[Rick Byers, 2016/02/02 04:24:16]

Two questions that I think should be covered by this comment:
1) How does this behave for multi-finger scenarios?  Is it "true if ANY finger
has moved beyond the slop region"?
2) What about a touchend that occurs during a scroll but doesn't cause a fling
(due to 0 velocity)?

Also for a long drag where all the touch events are consumed, it seems odd to
have this be false for the touchend, even though it was true for the touchmoves.
 Or perhaps the "fling-generating" means prior to touch disposition gesture
filtering?

[mustaq, 2016/02/04 21:17:21]

Done.

+    bool movedBeyondSlopRegion;
 
     // A unique identifier for the touch event.
     uint32_t uniqueTouchEventId;
 
     WebTouchEvent()
         : WebInputEvent(sizeof(WebTouchEvent))
         , touchesLength(0)
         , cancelable(true)
-        , causesScrollingIfUncanceled(false)
+        , movedBeyondSlopRegion(false)
         , uniqueTouchEventId(0)
     {
     }
 };
 
 #pragma pack(pop)
 
 } // namespace blink
 
 #endif