GitLab

Adjust underline positions so the lines won't get clipped. I
think that the inaccuracy may be occurring due to our
conversion from PangoFontDescriptions (usually containing a
point-based size) to a rounded pixel-based size and then
back to a PangoFontDescription. Luckily, RenderTextPango
will be replaced by RenderTextHarfBuzz soon.

Also delete some dead code in PlatformFontPango for
computing underline metrics.

BUG=393117
TEST=manual: checked that the "Import bookmarks now..."
     underline is visible after setting my UI font to
     "Ubuntu 11"

Review URL: https://codereview.chromium.org/509093004

Cr-Commit-Position: refs/heads/master@{#292537}