[RootLayerScrolls] Don't include PLSA header from paint_layer.h

This reduces the number of .cc files that include the PLSA header
from 196 to 107.

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: I846a7b5e3120e5cf60ba59002ba53c82d8099d88
Reviewed-on: https://chromium-review.googlesource.com/1111011
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Reviewed-by: Philip Rogers <pdr@chromium.org>
Reviewed-by: Steve Kobes <skobes@chromium.org>
Commit-Queue: Stefan Zager <szager@chromium.org>
Cr-Commit-Position: refs/heads/master@{#569671}
51 files changed