Make the content browser in ChromeOS honor the DOM UI font setting.

Make the content browser in ChromeOS honor the DOM  UI font setting.

At the moment, no font-family is specified. In that case, serif font is picked
by default by Chrome (exception being CJK for which sans-serif is picked).
Adding an attribute i18n-values for font-family will set up font-family
for the file. I'm not setting font-size because filebrowse.html uses em font-size
widely and the default value of 84% (set in locale_settings_cros.grd) will
disrupt the layout.

Change the DOM UI font for ChromeOS from 'Droid Sans' to 'Chrome Droid Sans'.
This may change again, but this matches the font used in the native UI (as
specified in gtkrc file) for now.

In addition, just as a 'sanitization', enclose font names (IDS_WEB_FONT_FAMILY)
with a space with a pair of single quotation marks.

BUG=chromiumos:6067 (http://crosbug.com/6067)
TEST=Build Chrome for ChromeOS and gmerge it to your build. Content browser does not use serif font any more. Instead, it uses 'Chrome Droid Sans'.

Review URL: http://codereview.chromium.org/3295010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@58949 0039d316-1c4b-4281-b951-d872f2087c98