Remove unsafe getFontMetrics methods

third_party/WebKit/Source/core/css/CSSToLengthConversionData.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 34 matching lines @@
 }
 
 CSSToLengthConversionData::FontSizes::FontSizes(const ComputedStyle* style,
                                                 const ComputedStyle* rootStyle)
     : FontSizes(style->computedFontSize(),
                 rootStyle ? rootStyle->computedFontSize() : 1.0f,
                 &style->font()) {}
 
 float CSSToLengthConversionData::FontSizes::ex() const {
   ASSERT(m_font);
+  const SimpleFontData* fontData = m_font->primaryFont();
+  DCHECK(fontData);
+
   // FIXME: We have a bug right now where the zoom will be applied twice to EX
   // units. We really need to compute EX using fontMetrics for the original
   // specifiedSize and not use our actual constructed layoutObject font.
-  if (!m_font->getFontMetrics().hasXHeight())
+  if (!fontData || !fontData->getFontMetrics().hasXHeight())
     return m_em / 2.0f;
-  return m_font->getFontMetrics().xHeight();
+  return fontData->getFontMetrics().xHeight();
 }
 
 float CSSToLengthConversionData::FontSizes::ch() const {
-  ASSERT(m_font);
-  return m_font->getFontMetrics().zeroWidth();
+  DCHECK(m_font);
+  const SimpleFontData* fontData = m_font->primaryFont();
+  DCHECK(fontData);
+  return fontData ? fontData->getFontMetrics().zeroWidth() : 0;
 }
 
 CSSToLengthConversionData::ViewportSize::ViewportSize(
     const LayoutViewItem& layoutViewItem)
     : m_size(!layoutViewItem.isNull()
                  ? layoutViewItem.viewportSizeForViewportUnits()
                  : DoubleSize()) {}
 
 CSSToLengthConversionData::CSSToLengthConversionData(
     const ComputedStyle* style,
@@ skipping 95 matching lines @@
     case CSSPrimitiveValue::UnitType::Chs:
       return value * chFontSize();
 
     default:
       ASSERT_NOT_REACHED();
       return 0;
   }
 }
 
 }  // namespace blink