Bug 1678771. Add test. r=hiro

We implement a new nsIDOMWindowUtils function sendNativeTouchpadPan to do this. It is only implemented on Windows here.

Depends on D122048

Differential Revision: https://phabricator.services.mozilla.com/D122049

widget/PuppetWidget.cpp

@@ -537,6 +537,17 @@ nsresult PuppetWidget::SynthesizeNativeTouchpadDoubleTap(
   return NS_OK;
 }
 
+nsresult PuppetWidget::SynthesizeNativeTouchpadPan(
+    TouchpadGesturePhase aEventPhase, LayoutDeviceIntPoint aPoint,
+    double aDeltaX, double aDeltaY, int32_t aModifierFlags) {
+  if (!mBrowserChild) {
+    return NS_ERROR_FAILURE;
+  }
+  mBrowserChild->SendSynthesizeNativeTouchpadPan(aEventPhase, aPoint, aDeltaX,
+                                                 aDeltaY, aModifierFlags);
+  return NS_OK;
+}
+
 void PuppetWidget::LockNativePointer() {
   if (!mBrowserChild) {
     return;