GitLab

DrawLineForDocumentMarker() only has one client (InlineTextBoxPainter),
so it makes sense for it to be a private helper.  Then we can also
remove the DocumentMarkerLineStyle GC enum.

BUG=424655
R=schenney@chromium.org
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2

Review-Url: https://codereview.chromium.org/2841153002
Cr-Commit-Position: refs/heads/master@{#467656}