Fix Linux |Font::GetAverageCharacterWidth()| always returning 0.

Pango metrics were not getting initialized.

BUG=none
TEST=New test added to font_unittest.cc.

Review URL: http://codereview.chromium.org/8289004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@105758 0039d316-1c4b-4281-b951-d872f2087c98
2 files changed