First Implementation of Snapped Points

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 6ff1983d7139c16be4b7604726a8c80db40dea7f..1522746a3a1133057a110da432b1115f2270cd5f 100644
--- a/ui/events/blink/input_handler_proxy.cc
+++ b/ui/events/blink/input_handler_proxy.cc
@@ -925,6 +925,9 @@ InputHandlerProxy::EventDisposition InputHandlerProxy::HandleGestureScrollEnd(
   DCHECK(expect_scroll_update_end_);
   expect_scroll_update_end_ = false;
 #endif
+  input_handler_->SnapAfterGestureScroll(
+      gfx::Point(gesture_event.x, gesture_event.y));
+
   if (ShouldAnimate(gesture_event.data.scroll_end.delta_units !=
                     blink::WebGestureEvent::ScrollUnits::kPixels)) {
     // Do nothing if the scroll is being animated; the scroll animation will
@@ -933,6 +936,7 @@ InputHandlerProxy::EventDisposition InputHandlerProxy::HandleGestureScrollEnd(
     cc::ScrollState scroll_state = CreateScrollStateForGesture(gesture_event);
     input_handler_->ScrollEnd(&scroll_state);
   }
+
   if (!gesture_scroll_on_impl_thread_)
     return DID_NOT_HANDLE;
 
@@ -1009,7 +1013,10 @@ InputHandlerProxy::EventDisposition InputHandlerProxy::HandleGestureFlingStart(
           WebPoint(gesture_event.global_x, gesture_event.global_y);
       fling_parameters_.modifiers = gesture_event.GetModifiers();
       fling_parameters_.source_device = gesture_event.source_device;
-      RequestAnimation();
+      if (AdjustFlingCurveToSnapPoints())
+        RequestAnimation();
+      else
+        fling_curve_.reset();
       return DID_HANDLE;
     }
     case cc::InputHandler::SCROLL_UNKNOWN:
@@ -1291,6 +1298,14 @@ void InputHandlerProxy::ExtendBoostedFlingTimeout(
   last_fling_boost_event_ = event;
 }
 
+bool InputHandlerProxy::AdjustFlingCurveToSnapPoints() {
+  gfx::Vector2dF original_offset;
+  fling_curve_->ComputeTotalScrollOffset(original_offset);
+  gfx::Vector2dF snapped_offset;
+  input_handler_->FindSnappedOffset(&snapped_offset, original_offset);
+  return fling_curve_->ResetCurveBySnappedOffset(snapped_offset);
+}
+
 void InputHandlerProxy::Animate(base::TimeTicks time) {
   // If using synchronous animate, then only expect Animate attempts started by
   // the synchronous system. Don't let the InputHandler try to Animate also.