Make DragController::CanProcessDrag() to pass point in frame to HitTestResult::IsSelected()

This patch changes |DragController::CanProcessDrag()| to pass point in frame
to |HitTestResult::IsSelected(point_in_frame)| instead of point in root,
because |HitTestResult::IsSelected()| calls |LayoutView::HitTest()| which
takes point in frame.

The change of "fast/lists/drag-into-marker.html" verifies this code change.

Change-Id: Ic95b16692fa73ea42ce62acac1fc868efd54a436
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2251607
Auto-Submit: Yoshifumi Inoue <yosin@chromium.org>
Reviewed-by: Kent Tamura <tkent@chromium.org>
Commit-Queue: Kent Tamura <tkent@chromium.org>
Commit-Queue: Yoshifumi Inoue <yosin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#780175}

third_party/blink/renderer/core/page/drag_controller.cc

@@ -712,12 +712,13 @@ bool DragController::CanProcessDrag(DragData* drag_data,
   if (!local_root.ContentLayoutObject())
     return false;
 
-  PhysicalOffset point = local_root.View()->ConvertFromRootFrame(
+  const PhysicalOffset point_in_local_root =
+      local_root.View()->ConvertFromRootFrame(
           PhysicalOffset::FromFloatPointRound(drag_data->ClientPosition()));
 
-  HitTestLocation location(point);
-  HitTestResult result =
-      local_root.GetEventHandler().HitTestResultAtLocation(location);
+  const HitTestResult result =
+      local_root.GetEventHandler().HitTestResultAtLocation(
+          HitTestLocation(point_in_local_root));
 
   if (!result.InnerNode())
     return false;
@@ -732,9 +733,16 @@ bool DragController::CanProcessDrag(DragData* drag_data,
     return false;
   }
 
-  if (did_initiate_drag_ && document_under_mouse_ == drag_initiator_ &&
-      result.IsSelected(location))
-    return false;
+  if (did_initiate_drag_ && document_under_mouse_ == drag_initiator_) {
+    const PhysicalOffset point_in_frame =
+        result.InnerNode()
+            ->GetDocument()
+            .GetFrame()
+            ->View()
+            ->ConvertFromRootFrame(PhysicalOffset::FromFloatPointRound(
+                drag_data->ClientPosition()));
+    return !result.IsSelected(HitTestLocation(point_in_frame));
+  }
 
   return true;
 }

third_party/blink/web_tests/fast/lists/drag-into-marker.html

@@ -69,7 +69,7 @@ selection_test(
         // can't get to. This (x, y) *should* be over the list marker.
         eventSender.mouseMoveTo(
             selection.computeLeft(ul) + 18,
-            selection.computeTop(li) + 3);
+            selection.computeTop(li) + li.offsetHeight / 2);
         eventSender.mouseUp();
     },
     [