Bug 1781209 - Swipe navigation does not work when kinetic scroll is disabled. r=botond

Differential Revision: https://phabricator.services.mozilla.com/D154239

modules/libpref/init/StaticPrefList.yaml

@@ -549,7 +549,12 @@
     value: true
     mirror: always
 
-# Mode to use when receiving kinetic scroll input.
+-   name: apz.gtk.pangesture.enabled
+    type: RelaxedAtomicBool
+    value: true
+    mirror: always
+
+# Mode to use when receiving pan gesture input.
 #
 #  * 0: Auto mode (uses the default behavior, subject to change).
 #  * 1: Page mode: Uses gtk deltas as a percentage of the page size to scroll. This mode matches:
@@ -560,17 +565,17 @@
 #
 #    https://webkit-search.igalia.com/webkit/rev/215039ef09d6bfd6e088175bfe30788d95b9705d/Source/WebKit/Shared/gtk/WebEventFactory.cpp#265-296
 #    (multiplied then by pixelsPerLineStep which in GNOME-web is 40).
--   name: apz.gtk.kinetic_scroll.delta_mode
+-   name: apz.gtk.pangesture.delta_mode
     type: uint32_t
     value: 0
     mirror: always
 
--   name: apz.gtk.kinetic_scroll.page_delta_mode_multiplier
+-   name: apz.gtk.pangesture.page_delta_mode_multiplier
     type: float
     value: 1.0f
     mirror: always
 
--   name: apz.gtk.kinetic_scroll.pixel_delta_mode_multiplier
+-   name: apz.gtk.pangesture.pixel_delta_mode_multiplier
     type: float
     value: 40.0f
     mirror: always

widget/gtk/nsWindow.cpp

@@ -4727,7 +4727,7 @@ void nsWindow::OnScrollEvent(GdkEventScroll* aEvent) {
       GdkInputSource source = gdk_device_get_source(device);
       if (source == GDK_SOURCE_TOUCHSCREEN || source == GDK_SOURCE_TOUCHPAD ||
           mCurrentSynthesizedTouchpadPan.mTouchpadGesturePhase.isSome()) {
-        if (StaticPrefs::apz_gtk_kinetic_scroll_enabled() &&
+        if (StaticPrefs::apz_gtk_pangesture_enabled() &&
             gtk_check_version(3, 20, 0) == nullptr) {
           static auto sGdkEventIsScrollStopEvent =
               (gboolean(*)(const GdkEvent*))dlsym(
@@ -4773,14 +4773,14 @@ void nsWindow::OnScrollEvent(GdkEventScroll* aEvent) {
           mCurrentSynthesizedTouchpadPan.mTouchpadGesturePhase.reset();
 
           const bool isPageMode =
-              StaticPrefs::apz_gtk_kinetic_scroll_delta_mode() != 2;
+              StaticPrefs::apz_gtk_pangesture_delta_mode() != 2;
           const double multiplier =
               isPageMode
-                  ? StaticPrefs::
-                        apz_gtk_kinetic_scroll_page_delta_mode_multiplier()
+                  ? StaticPrefs::apz_gtk_pangesture_page_delta_mode_multiplier()
                   : StaticPrefs::
-                            apz_gtk_kinetic_scroll_pixel_delta_mode_multiplier() *
+                            apz_gtk_pangesture_pixel_delta_mode_multiplier() *
                         FractionalScaleFactor();
+
           ScreenPoint deltas(float(aEvent->delta_x * multiplier),
                              float(aEvent->delta_y * multiplier));
 
@@ -4791,7 +4791,8 @@ void nsWindow::OnScrollEvent(GdkEventScroll* aEvent) {
               KeymapWrapper::ComputeKeyModifiers(aEvent->state));
           panEvent.mDeltaType = isPageMode ? PanGestureInput::PANDELTA_PAGE
                                            : PanGestureInput::PANDELTA_PIXEL;
-          panEvent.mSimulateMomentum = true;
+          panEvent.mSimulateMomentum =
+              StaticPrefs::apz_gtk_kinetic_scroll_enabled();
 
           panEvent
               .mRequiresContentResponseIfCannotScrollHorizontallyInStartDirection =