[RootLayerScrolls] Eliminate calls to LocalFrameView::VisibleContent*

VisibleContentRect() and VisibleContentSize() are based on
scroll_offset_ (which is always (0, 0)), and Size() with scrollbars
possible excluded -- but there are no scrollbars any more. Replace
all of the calls with Size().

BUG=823365
TBR=dmazzoni@chromium.org

Cq-Include-Trybots: luci.chromium.try:linux_layout_tests_slimming_paint_v2;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: Ieb41515bf53e20762aca9f81df413ebb397c9f5d
Reviewed-on: https://chromium-review.googlesource.com/1112067
Commit-Queue: Stefan Zager <szager@chromium.org>
Reviewed-by: Steve Kobes <skobes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#569944}
24 files changed