Redefined the bit WebTouchEvent.causesScrollingIfUncanceled.

ui/events/blink/blink_event_util.cc

Index: ui/events/blink/blink_event_util.cc
diff --git a/ui/events/blink/blink_event_util.cc b/ui/events/blink/blink_event_util.cc
index d268662044ba9063821ef47fd0253efdd1615f4d..40adab2a6d7c285ea6b5adbb53579263cfd8ba44 100644
--- a/ui/events/blink/blink_event_util.cc
+++ b/ui/events/blink/blink_event_util.cc
@@ -179,7 +179,7 @@ WebTouchPoint CreateWebTouchPoint(const MotionEvent& event,
 
 blink::WebTouchEvent CreateWebTouchEventFromMotionEvent(
     const MotionEvent& event,
-    bool may_cause_scrolling) {
+    bool moved_beyond_slop_region) {
   static_assert(static_cast<int>(MotionEvent::MAX_TOUCH_POINT_COUNT) ==
                     static_cast<int>(blink::WebTouchEvent::touchesLengthCap),
                 "inconsistent maximum number of active touch points");
@@ -189,8 +189,8 @@ blink::WebTouchEvent CreateWebTouchEventFromMotionEvent(
   result.type = ToWebInputEventType(event.GetAction());
   result.cancelable = (result.type != WebInputEvent::TouchCancel);
   result.timeStampSeconds =
-      (event.GetEventTime() - base::TimeTicks()).InSecondsF(),
-  result.causesScrollingIfUncanceled = may_cause_scrolling;
+      (event.GetEventTime() - base::TimeTicks()).InSecondsF();
+  result.movedBeyondSlopRegion = moved_beyond_slop_region;
   result.modifiers = EventFlagsToWebEventModifiers(event.GetFlags());
   DCHECK_NE(event.GetUniqueEventId(), 0U);
   result.uniqueTouchEventId = event.GetUniqueEventId();
@@ -205,6 +205,22 @@ blink::WebTouchEvent CreateWebTouchEventFromMotionEvent(
   return result;
 }
 
+bool IsTouchSequenceStart(const MotionEvent& event) {

[tdresser, 2016/02/05 14:19:00]

Isn't this equivalent to event.GetAction() == ACTION_DOWN?

http://developer.android.com/reference/android/view/MotionEvent.html#ACTION_DOWN

[mustaq, 2016/02/05 15:29:18]

Thanks for the catch: I was trying to return true on multi-tap, but my
filtered_gesture_provider logic works as-is with your suggestion.

+  if (ToWebInputEventType(event.GetAction()) != WebInputEvent::TouchStart)
+    return false;
+
+  size_t num_touches = event.GetPointerCount();
+  if (!num_touches)
+    return false;
+
+  for (size_t i = 0; i < num_touches; i++) {
+    if (ToWebTouchPointState(event, i) != WebTouchPoint::StatePressed)
+      return false;
+  }
+
+  return true;
+}
+
 int EventFlagsToWebEventModifiers(int flags) {
   int modifiers = 0;