[LayoutNG] Compute baseline from fragment tree

third_party/WebKit/Source/core/layout/ng/ng_box_fragment.h

Index: third_party/WebKit/Source/core/layout/ng/ng_box_fragment.h
diff --git a/third_party/WebKit/Source/core/layout/ng/ng_box_fragment.h b/third_party/WebKit/Source/core/layout/ng/ng_box_fragment.h
index 60c14c811261e9444068ed94127284e53c2da57c..b14c1af6fada839032beb26abae3f31c6ac2a6fa 100644
--- a/third_party/WebKit/Source/core/layout/ng/ng_box_fragment.h
+++ b/third_party/WebKit/Source/core/layout/ng/ng_box_fragment.h
@@ -12,6 +12,7 @@
 
 namespace blink {
 
+struct NGLineHeightMetrics;
 struct NGLogicalSize;
 
 class CORE_EXPORT NGBoxFragment final : public NGFragment {
@@ -22,6 +23,12 @@ class CORE_EXPORT NGBoxFragment final : public NGFragment {
 
   // Returns the total size, including the contents outside of the border-box.
   NGLogicalSize OverflowSize() const;
+
+  // Compute baseline metrics (ascent/descent) for this box.
+  //
+  // Baseline requests must be added to constraint space when this fragment was
+  // laid out.
+  NGLineHeightMetrics BaselineMetrics(const NGBaselineRequest&) const;
 };
 
 DEFINE_TYPE_CASTS(NGBoxFragment,