[FragmentItem] Implement hit-testing text items

This patch implements hit-testing text items, that was not
implemented in the initial hit-test implementation in r720001
<crrev.com/c/1935773>.

The LayoutNG specific logic for |NodeForHitTest()| was moved
to |LayoutObject| in r720148 to share the logic with
|NGFragmentItem|.

8 failures, ~110 passes.

Bug: 982194
Change-Id: I4a1f3414cb1d299d4f1d6f57e64881f6aeddbff8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1943719Reviewed-by: Ian Kilpatrick <ikilpatrick@chromium.org>
Commit-Queue: Koji Ishii <kojii@chromium.org>
Cr-Commit-Position: refs/heads/master@{#720778}

third_party/blink/renderer/core/layout/ng/inline/ng_fragment_item.h

@@ -99,6 +99,7 @@ class CORE_EXPORT NGFragmentItem : public DisplayItemClient {
     return const_cast<LayoutObject*>(layout_object_);
   }
   Node* GetNode() const { return layout_object_->GetNode(); }
+  Node* NodeForHitTest() const { return layout_object_->NodeForHitTest(); }
   bool HasSameParent(const NGFragmentItem& other) const;
 
   wtf_size_t DeltaToNextForSameLayoutObject() const {

third_party/blink/renderer/core/paint/ng/ng_box_fragment_painter.cc

@@ -70,12 +70,23 @@ inline bool IsVisibleToPaint(const NGFragmentItem& item,
          style.Visibility() == EVisibility::kVisible;
 }
 
+inline bool IsVisibleToHitTest(const HitTestRequest& request,
+                               const ComputedStyle& style) {
+  return request.IgnorePointerEventsNone() ||
+         style.PointerEvents() != EPointerEvents::kNone;
+}
+
+inline bool IsVisibleToHitTest(const NGFragmentItem& item,
+                               const HitTestRequest& request) {
+  const ComputedStyle& style = item.Style();
+  return IsVisibleToPaint(item, style) && IsVisibleToHitTest(request, style);
+}
+
 bool FragmentVisibleToHitTestRequest(const NGPhysicalFragment& fragment,
                                      const HitTestRequest& request) {
   const ComputedStyle& style = fragment.Style();
   return IsVisibleToPaint(fragment, style) &&
-         (request.IgnorePointerEventsNone() ||
-          style.PointerEvents() != EPointerEvents::kNone);
+         IsVisibleToHitTest(request, style);
 }
 
 // Hit tests inline ancestor elements of |fragment| who do not have their own
@@ -1549,6 +1560,45 @@ bool NGBoxFragmentPainter::HitTestTextFragment(
   return false;
 }
 
+bool NGBoxFragmentPainter::HitTestTextItem(
+    HitTestResult& result,
+    const NGFragmentItem& text_item,
+    const HitTestLocation& hit_test_location,
+    const PhysicalOffset& physical_offset,
+    HitTestAction action) {
+  DCHECK(text_item.IsText());
+
+  if (action != kHitTestForeground)
+    return false;
+
+  PhysicalRect border_rect(physical_offset, text_item.Size());
+
+  // TODO(layout-dev): Clip to line-top/bottom.
+  PhysicalRect rect(PixelSnappedIntRect(border_rect));
+  if (UNLIKELY(result.GetHitTestRequest().GetType() &
+               HitTestRequest::kHitTestVisualOverflow)) {
+    rect = text_item.SelfInkOverflow();
+    rect.Move(border_rect.offset);
+  }
+
+  if (IsVisibleToHitTest(text_item, result.GetHitTestRequest()) &&
+      hit_test_location.Intersects(rect)) {
+    Node* node = text_item.NodeForHitTest();
+    if (!result.InnerNode() && node) {
+      PhysicalOffset point =
+          hit_test_location.Point() - physical_offset + text_item.Offset();
+      result.SetNodeAndPosition(node, point);
+    }
+
+    if (result.AddNodeToListBasedTestResult(node, hit_test_location, rect) ==
+        kStopHitTesting) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
 // Replicates logic in legacy InlineFlowBox::NodeAtPoint().
 bool NGBoxFragmentPainter::HitTestLineBoxFragment(
     HitTestResult& result,
@@ -1768,7 +1818,9 @@ bool NGBoxFragmentPainter::HitTestItemsChildren(
 
     const PhysicalOffset child_offset = item->Offset() + accumulated_offset;
     if (item->IsText()) {
-      // TODO(kojii): Implement for a text item.
+      if (HitTestTextItem(result, *item, hit_test_location, child_offset,
+                          action))
+        return true;
     } else if (item->Type() == NGFragmentItem::kLine) {
       const NGPhysicalLineBoxFragment* child_fragment = item->LineBoxFragment();
       DCHECK(child_fragment);

third_party/blink/renderer/core/paint/ng/ng_box_fragment_painter.h

@@ -202,6 +202,11 @@ class NGBoxFragmentPainter : public BoxPainterBase {
                            const HitTestLocation& hit_test_location,
                            const PhysicalOffset& physical_offset,
                            HitTestAction);
+  bool HitTestTextItem(HitTestResult& result,
+                       const NGFragmentItem& text_item,
+                       const HitTestLocation& hit_test_location,
+                       const PhysicalOffset& physical_offset,
+                       HitTestAction action);
 
   // Hit tests the given line box fragment.
   // @param physical_offset Physical offset of the line box fragment in paint