Remove NGPaintFragment in LayoutNGBlockFlowMixin::Paint

This patch removes |NGPaintFragment| support in |Paint|.

By eliminating |NGFragmentItem| specific code,
|LayoutNGBlockFlowMixin::Paint| becomes equivalent to
|LayoutNGMixin::Paint| that it is removed.

Bug: 1154531
Change-Id: Iac72b27256a5e6219eb49a689e671f0477f03e3d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2567145
Commit-Queue: Koji Ishii <kojii@chromium.org>
Commit-Queue: Kent Tamura <tkent@chromium.org>
Reviewed-by: Yoshifumi Inoue <yosin@chromium.org>
Reviewed-by: Kent Tamura <tkent@chromium.org>
Auto-Submit: Koji Ishii <kojii@chromium.org>
Cr-Commit-Position: refs/heads/master@{#832702}

third_party/blink/renderer/core/layout/ng/layout_ng_block_flow_mixin.cc

@@ -216,49 +216,6 @@ void LayoutNGBlockFlowMixin<Base>::SetPaintFragment(
   }
 }
 
-template <typename Base>
-void LayoutNGBlockFlowMixin<Base>::Paint(const PaintInfo& paint_info) const {
-  // When |this| is NG block fragmented, the painter should traverse fragments
-  // instead of |LayoutObject|, because this function cannot handle block
-  // fragmented objects. We can come here only when |this| cannot traverse
-  // fragments, or the parent is legacy.
-  DCHECK(!Base::CanTraversePhysicalFragments() ||
-         !Base::Parent()->CanTraversePhysicalFragments());
-  DCHECK_LE(Base::PhysicalFragmentCount(), 1u);
-
-  // Avoid painting dirty objects because descendants maybe already destroyed.
-  if (UNLIKELY(Base::NeedsLayout() &&
-               !Base::ChildLayoutBlockedByDisplayLock())) {
-    NOTREACHED();
-    return;
-  }
-
-  if (UNLIKELY(RuntimeEnabledFeatures::LayoutNGFragmentItemEnabled())) {
-    if (Base::PhysicalFragmentCount()) {
-      const NGPhysicalBoxFragment* fragment = Base::GetPhysicalFragment(0);
-      DCHECK(fragment);
-      if (fragment->HasItems()) {
-        NGBoxFragmentPainter(*fragment).Paint(paint_info);
-        return;
-      }
-    }
-  }
-
-  if (const NGPaintFragment* paint_fragment = PaintFragment()) {
-    NGBoxFragmentPainter(*paint_fragment).Paint(paint_info);
-    return;
-  }
-
-  if (Base::PhysicalFragmentCount()) {
-    const NGPhysicalBoxFragment* fragment = Base::GetPhysicalFragment(0);
-    DCHECK(fragment);
-    NGBoxFragmentPainter(*fragment).Paint(paint_info);
-    return;
-  }
-
-  Base::Paint(paint_info);
-}
-
 template <typename Base>
 bool LayoutNGBlockFlowMixin<Base>::NodeAtPoint(
     HitTestResult& result,

third_party/blink/renderer/core/layout/ng/layout_ng_block_flow_mixin.h

@@ -41,8 +41,6 @@ class LayoutNGBlockFlowMixin : public LayoutNGMixin<Base> {
   LayoutUnit FirstLineBoxBaseline() const final;
   LayoutUnit InlineBlockBaseline(LineDirectionMode) const final;
 
-  void Paint(const PaintInfo&) const override;
-
   bool NodeAtPoint(HitTestResult&,
                    const HitTestLocation&,
                    const PhysicalOffset& accumulated_offset,

third_party/blink/renderer/core/layout/ng/layout_ng_mixin.cc

@@ -55,7 +55,11 @@ void LayoutNGMixin<Base>::Paint(const PaintInfo& paint_info) const {
     const NGPhysicalBoxFragment* fragment = Base::GetPhysicalFragment(0);
     DCHECK(fragment);
     NGBoxFragmentPainter(*fragment).Paint(paint_info);
+    return;
   }
+
+  NOTREACHED();
+  Base::Paint(paint_info);
 }
 
 template <typename Base>