Implement support for touch-action: pan-x/pan-y in chromium

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 e30ecce8259c9d3a63156b417f12b5e1155cabe9..effeecb3d162b8f6d6b02225250bdeacabf1bcac 100644
--- a/content/common/input/synthetic_web_input_event_builders.cc
+++ b/content/common/input/synthetic_web_input_event_builders.cc
@@ -89,6 +89,16 @@ WebGestureEvent SyntheticWebGestureEventBuilder::Build(
   return result;
 }
 
+WebGestureEvent SyntheticWebGestureEventBuilder::BuildScrollBegin(
+    float dx_hint,
+    float dy_hint) {
+  WebGestureEvent result = Build(WebInputEvent::GestureScrollBegin,
+                                 WebGestureEvent::Touchscreen);
+  result.data.scrollBegin.deltaXHint = dx_hint;
+  result.data.scrollBegin.deltaYHint = dy_hint;
+  return result;
+}
+
 WebGestureEvent SyntheticWebGestureEventBuilder::BuildScrollUpdate(
     float dx,
     float dy,