Cleanup pre-refresh code in new_tab_button.cc, and its dependencies.

This also does a few other things, e.g. SkPath -> gfx::Path, cleaning up
pre-refresh stuff in tab_unittest.cc, etc.

Bug: none
Change-Id: I880b950d0432a463c8f2a79c776a5e563d99a07e
Reviewed-on: https://chromium-review.googlesource.com/1229368
Reviewed-by: Evan Stade <estade@chromium.org>
Reviewed-by: Allen Bauer <kylixrd@chromium.org>
Commit-Queue: Peter Kasting <pkasting@chromium.org>
Cr-Commit-Position: refs/heads/master@{#592056}
16 files changed