Remove unsafe getFontMetrics methods

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

Index: third_party/WebKit/Source/core/css/CSSToLengthConversionData.cpp
diff --git a/third_party/WebKit/Source/core/css/CSSToLengthConversionData.cpp b/third_party/WebKit/Source/core/css/CSSToLengthConversionData.cpp
index 0874a35243ff5cccb3d434e3ae3d0cf6992bb036..e1f3d7f441db8e6986aa7b2873fd1f8e8ace53a1 100644
--- a/third_party/WebKit/Source/core/css/CSSToLengthConversionData.cpp
+++ b/third_party/WebKit/Source/core/css/CSSToLengthConversionData.cpp
@@ -52,17 +52,22 @@ CSSToLengthConversionData::FontSizes::FontSizes(const ComputedStyle* style,
 
 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(