Touchpad scroll latching enabled for Mac behind flag.

ui/events/blink/input_handler_proxy.cc

Index: ui/events/blink/input_handler_proxy.cc
diff --git a/ui/events/blink/input_handler_proxy.cc b/ui/events/blink/input_handler_proxy.cc
index 115c21a9c70a4b281fac7705bfa7520f122e5f4a..3e8c9d71cc232933f6a7d6644ff10712db876587 100644
--- a/ui/events/blink/input_handler_proxy.cc
+++ b/ui/events/blink/input_handler_proxy.cc
@@ -131,6 +131,10 @@ cc::ScrollState CreateScrollStateForGesture(const WebGestureEvent& event) {
       scroll_state_data.position_x = event.x;
       scroll_state_data.position_y = event.y;
       scroll_state_data.is_beginning = true;
+      // On Mac flings are aslo scrolls.

[tdresser, 2016/08/18 13:59:47]

aslo -> also

Or perhaps:
// On Mac, a GestureScrollBegin in the inertial phase indicates a fling start.

[sahel, 2016/08/18 15:41:56]

Done.

+      if (event.data.scrollBegin.inertialPhase ==
+          WebGestureEvent::MomentumPhase)
+        scroll_state_data.is_in_inertial_phase = true;
       break;
     case WebInputEvent::GestureFlingStart:
       scroll_state_data.velocity_x = event.data.flingStart.velocityX;