Expose whether a touch event may cause scrolling if uncanceled

public/web/WebInputEvent.h

Index: public/web/WebInputEvent.h
diff --git a/public/web/WebInputEvent.h b/public/web/WebInputEvent.h
index 6db55bb14b9957c39528adb9e57ed50cd6cb6dec..ab7e4aba73b7186d8a9a70ec2efc8ebdd5da7618 100644
--- a/public/web/WebInputEvent.h
+++ b/public/web/WebInputEvent.h
@@ -166,14 +166,6 @@ public:
         // Left/right modifiers for keyboard events.
         IsLeft           = 1 << 11,
         IsRight          = 1 << 12,
-
-        // Last input event to be sent for the current vsync interval. If this
-        // flag is set, the sender guarantees that no more input events will be
-        // delivered until the next vsync and the receiver can schedule
-        // rendering accordingly. If it isn't set, the receiver should not make
-        // any assumptions about the delivery times of future input events
-        // w.r.t. vsync.
-        IsLastInputEventForCurrentVSync = 1 << 13,
     };
 
     static const int InputModifiers = ShiftKey | ControlKey | AltKey | MetaKey;
@@ -504,10 +496,19 @@ public:
     // See comment at the top for why an int is used here instead of a bool.
     int 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.
+    // See comment at the top for why an int is used here instead of a bool.
+    int causesScrollingIfUncanceled;
+
     WebTouchEvent()
         : WebInputEvent(sizeof(WebTouchEvent))
         , touchesLength(0)
         , cancelable(true)
+        , causesScrollingIfUncanceled(false)
     {
     }
 };