[RLS] Remove !RLS code in CLM and background_image_geometry

This patch removes the !RLS codepaths in CompositedLayerMapping (CLM)
and background_image_geometry now that Root Layer Scrolling (RLS) has
launched.

Bug: 823365
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
Change-Id: Id07239b22bb96fa7e4d0d3c41d82b61aa9eb5090
Reviewed-on: https://chromium-review.googlesource.com/1071871
Commit-Queue: Philip Rogers <pdr@chromium.org>
Commit-Queue: Chris Harrelson <chrishtr@chromium.org>
Reviewed-by: Chris Harrelson <chrishtr@chromium.org>
Reviewed-by: Steve Kobes <skobes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#561588}
2 files changed