Remove unsafe getFontMetrics methods

third_party/WebKit/Source/core/layout/LayoutBlock.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2007 David Smith (catfish.man@gmail.com)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc.
  *               All rights reserved.
  * Copyright (C) Research In Motion Limited 2010. 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
@@ skipping 1672 matching lines @@
 
     return LayoutBox::baselinePosition(baselineType, firstLine, direction,
                                        linePositionMode);
   }
 
   // If we're not replaced, we'll only get called with
   // PositionOfInteriorLineBoxes.
   // Note that inline-block counts as replaced here.
   ASSERT(linePositionMode == PositionOfInteriorLineBoxes);
 
-  const FontMetrics& fontMetrics = style(firstLine)->getFontMetrics();
+  const SimpleFontData* fontData = style(firstLine)->font().primaryFont();
+  DCHECK(fontData);
+  if (!fontData)
+    return -1;

[wkorman, 2016/10/13 22:54:30]

Is -1 the correct error value? I see LayoutTheme::baselinePosition() which is
also used as a return value in this method returns 0 in a different
less-error-ish case (!o->isBox()).

[eae, 2016/10/13 23:09:58]

Yeah, -1 is the magic value for unknown baseline.

+
+  const FontMetrics& fontMetrics = fontData->getFontMetrics();
   return (fontMetrics.ascent(baselineType) +
           (lineHeight(firstLine, direction, linePositionMode) -
            fontMetrics.height()) /
               2)
       .toInt();
 }
 
 LayoutUnit LayoutBlock::minLineHeightForReplacedObject(
     bool isFirstLine,
     LayoutUnit replacedHeight) const {
@@ skipping 48 matching lines @@
   for (LayoutBox* curr = lastChildBox(); curr;
        curr = curr->previousSiblingBox()) {
     if (!curr->isFloatingOrOutOfFlowPositioned()) {
       haveNormalFlowChild = true;
       int result = curr->inlineBlockBaseline(lineDirection);
       if (result != -1)
         return (curr->logicalTop() + result)
             .toInt();  // Translate to our coordinate space.
     }
   }
-  if (!haveNormalFlowChild && hasLineIfEmpty()) {
-    const FontMetrics& fontMetrics = firstLineStyle()->getFontMetrics();
+  const SimpleFontData* fontData = firstLineStyle()->font().primaryFont();
+  if (!haveNormalFlowChild && hasLineIfEmpty() && fontData) {

[wkorman, 2016/10/13 22:54:30]

Perhaps worth putting fontData first to save on checking others if not available
since hasLineIfEmpty() is a virtual method. Though obviously this situation
should be very rare so not super impactful.

[eae, 2016/10/13 23:09:58]

Acknowledged.

+    const FontMetrics& fontMetrics = fontData->getFontMetrics();
     return (fontMetrics.ascent() +
             (lineHeight(true, lineDirection, PositionOfInteriorLineBoxes) -
              fontMetrics.height()) /
                 2 +
             (lineDirection == HorizontalLine ? borderTop() + paddingTop()
                                              : borderRight() + paddingRight()))
         .toInt();
   }
   return -1;
 }
@@ skipping 428 matching lines @@
   }
 
   return availableHeight;
 }
 
 bool LayoutBlock::hasDefiniteLogicalHeight() const {
   return availableLogicalHeightForPercentageComputation() != LayoutUnit(-1);
 }
 
 }  // namespace blink