Fix 'text-underline-position: under' to use em height ascent/descent

third_party/WebKit/Source/core/layout/line/InlineFlowBox.cpp

 /*
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc.
  *               All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 880 matching lines @@
       line_bottom_including_margins =
           std::max(line_bottom, line_bottom_including_margins);
     }
 
     if (GetLineLayoutItem().Style()->IsFlippedLinesWritingMode())
       FlipLinesInBlockDirection(line_top_including_margins,
                                 line_bottom_including_margins);
   }
 }
 
-LayoutUnit InlineFlowBox::MaxLogicalBottomForUnderline(
-    LineLayoutItem decoration_object,
-    LayoutUnit max_logical_bottom) const {
+LayoutUnit InlineFlowBox::FarthestPositionForUnderline(
+    LineLayoutItem decorating_box,
+    LineVerticalPositionType position_type,
+    FontBaseline baseline_type,
+    LayoutUnit farthest) const {
   for (InlineBox* curr = FirstChild(); curr; curr = curr->NextOnLine()) {
     if (curr->GetLineLayoutItem().IsOutOfFlowPositioned())
       continue;  // Positioned placeholders don't affect calculations.
-
-    // If the text decoration isn't in effect on the child, it must be outside
-    // of |decorationObject|.
-    if (!(curr->LineStyleRef().TextDecorationsInEffect() &
-          kTextDecorationUnderline))
-      continue;
-
-    if (decoration_object && decoration_object.IsLayoutInline() &&
-        !IsAncestorAndWithinBlock(decoration_object, curr->GetLineLayoutItem()))
-      continue;
-
-    if (curr->IsInlineFlowBox()) {
-      max_logical_bottom = ToInlineFlowBox(curr)->MaxLogicalBottomForUnderline(
-          decoration_object, max_logical_bottom);
-    } else if (curr->IsInlineTextBox()) {
-      max_logical_bottom = std::max(max_logical_bottom, curr->LogicalBottom());
-    }
-  }
-  return max_logical_bottom;
-}
-
-LayoutUnit InlineFlowBox::MinLogicalTopForUnderline(
-    LineLayoutItem decoration_object,
-    LayoutUnit min_logical_top) const {
-  for (InlineBox* curr = FirstChild(); curr; curr = curr->NextOnLine()) {
-    if (curr->GetLineLayoutItem().IsOutOfFlowPositioned())
-      continue;  // Positioned placeholders don't affect calculations.
 
     // If the text decoration isn't in effect on the child, it must be outside
     // of |decorationObject|.
     if (!(curr->LineStyleRef().TextDecorationsInEffect() &
           kTextDecorationUnderline))
       continue;
 
-    if (decoration_object && decoration_object.IsLayoutInline() &&
-        !IsAncestorAndWithinBlock(decoration_object, curr->GetLineLayoutItem()))
+    if (decorating_box && decorating_box.IsLayoutInline() &&
+        !IsAncestorAndWithinBlock(decorating_box, curr->GetLineLayoutItem()))
       continue;
 
     if (curr->IsInlineFlowBox()) {
-      min_logical_top = ToInlineFlowBox(curr)->MinLogicalTopForUnderline(
-          decoration_object, min_logical_top);
+      farthest = ToInlineFlowBox(curr)->FarthestPositionForUnderline(
+          decorating_box, position_type, baseline_type, farthest);
     } else if (curr->IsInlineTextBox()) {
-      min_logical_top = std::min(min_logical_top, curr->LogicalTop());
+      LayoutUnit position =
+          ToInlineTextBox(curr)->VerticalPosition(position_type, baseline_type);
+      if (IsLineOverSide(position_type))
+        farthest = std::min(farthest, position);
+      else
+        farthest = std::max(farthest, position);
     }
   }
-  return min_logical_top;
+  return farthest;
 }
 
 void InlineFlowBox::FlipLinesInBlockDirection(LayoutUnit line_top,
                                               LayoutUnit line_bottom) {
   // Flip the box on the line such that the top is now relative to the
   // lineBottom instead of the lineTop.
   SetLogicalTop(line_bottom - (LogicalTop() - line_top) - LogicalHeight());
 
   for (InlineBox* curr = FirstChild(); curr; curr = curr->NextOnLine()) {
     if (curr->GetLineLayoutItem().IsOutOfFlowPositioned())
@@ skipping 790 matching lines @@
     DCHECK_EQ(child->prevOnLine(), prev);
     prev = child;
   }
   DCHECK_EQ(prev, m_lastChild);
 #endif
 }
 
 #endif
 
 }  // namespace blink