Move GraphicsLayer text dumping out of platform.

The immediate motivation for this patch is to pave the way to move
stuff out of platform/scroll and into core/. That aside, it probably
makes more sense to put this kind of code in core/ rather than
platform/.

BUG=823365
R=skobes@chromium.org,pdr@chromium.org

Cq-Include-Trybots: luci.chromium.try:linux_layout_tests_slimming_paint_v2;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: I0859fbfa6ddf82c607a36cbbd0bee77e49a3c0b0
Reviewed-on: https://chromium-review.googlesource.com/1131000
Reviewed-by: Steve Kobes <skobes@chromium.org>
Reviewed-by: Philip Rogers <pdr@chromium.org>
Commit-Queue: Stefan Zager <szager@chromium.org>
Cr-Commit-Position: refs/heads/master@{#574081}
9 files changed