Fill capHeight and maxCharWidth on Mac.

BUG=skia:3924

Review URL: https://codereview.chromium.org/1164423006
diff --git a/src/ports/SkFontHost_mac.cpp b/src/ports/SkFontHost_mac.cpp
index a184a8b..22e2954 100755
--- a/src/ports/SkFontHost_mac.cpp
+++ b/src/ports/SkFontHost_mac.cpp
@@ -1393,7 +1393,9 @@
     metrics->fAvgCharWidth = CGToScalar( CGRectGetWidth_inline(theBounds));
     metrics->fXMin         = CGToScalar( CGRectGetMinX_inline(theBounds));
     metrics->fXMax         = CGToScalar( CGRectGetMaxX_inline(theBounds));
+    metrics->fMaxCharWidth = metrics->fXMax - metrics->fXMin;
     metrics->fXHeight      = CGToScalar( CTFontGetXHeight(fCTFont));
+    metrics->fCapHeight    = CGToScalar( CTFontGetCapHeight(fCTFont));
     metrics->fUnderlineThickness = CGToScalar( CTFontGetUnderlineThickness(fCTFont));
     metrics->fUnderlinePosition = -CGToScalar( CTFontGetUnderlinePosition(fCTFont));