Touch Action could cause wheel gestures to be filtered.

content/common/input/synthetic_web_input_event_builders.cc

Index: content/common/input/synthetic_web_input_event_builders.cc
diff --git a/content/common/input/synthetic_web_input_event_builders.cc b/content/common/input/synthetic_web_input_event_builders.cc
index c68c689c09be8fa8ac679127f4477d997c4d25cf..e7e7d49176a13a81de4ade4130cdb6e7eb061e1d 100644
--- a/content/common/input/synthetic_web_input_event_builders.cc
+++ b/content/common/input/synthetic_web_input_event_builders.cc
@@ -118,9 +118,10 @@ WebGestureEvent SyntheticWebGestureEventBuilder::Build(
 
 WebGestureEvent SyntheticWebGestureEventBuilder::BuildScrollBegin(
     float dx_hint,
-    float dy_hint) {
-  WebGestureEvent result = Build(WebInputEvent::GestureScrollBegin,
-                                 blink::WebGestureDeviceTouchscreen);
+    float dy_hint,
+    blink::WebGestureDevice source_device) {
+  WebGestureEvent result =
+      Build(WebInputEvent::GestureScrollBegin, source_device);
   result.data.scrollBegin.deltaXHint = dx_hint;
   result.data.scrollBegin.deltaYHint = dy_hint;
   return result;