[RootLayerScrolls] Get rid of obsolete kInFrameCoordinates constant

"Frame content" coordinates are no longer a thing.

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

Cq-Include-Trybots: luci.chromium.try:linux_layout_tests_slimming_paint_v2;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: I6e82c57a8bc9008402407639d4e2e4a60161e337
Reviewed-on: https://chromium-review.googlesource.com/1117889
Commit-Queue: Stefan Zager <szager@chromium.org>
Reviewed-by: Chris Harrelson <chrishtr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#571247}
3 files changed