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 9f4722a2053b6261cdfb42e59823436c0ac1dd5e..9767f31a9be6c015377bbc8c810a03045e2843d5 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;
@@ -496,10 +488,17 @@ public:
     // See comment at the top for why an int is used here instead of a bool.
     int cancelable;
 
+    // Whether the event may cause scrolling if not canceled. This will be true
+    // for touchmove events after the platform slop region has been exceeded
+    // and touchend events that induce a fling.
+    // See comment at the top for why an int is used here instead of a bool.
+    int mayCauseScrollingIfUncanceled;

[Rick Byers, 2014/11/10 18:56:04]

Nit: if it really "will be true for ..." then why call it "may..."?  Maybe just
"causesScrollingIfUncanceled"?

Do you plan to take the touch-action filter into account in setting this bit?

+
     WebTouchEvent()
         : WebInputEvent(sizeof(WebTouchEvent))
         , touchesLength(0)
         , cancelable(true)
+        , mayCauseScrollingIfUncanceled(false)
     {
     }
 };