The system_health.memory_mobile and system_health.memory_desktop benchmarks fail flakily with RootLayerScrolling enabled.

See the following trybot runs, which all report failure of SystemHealthBenchmarkSmokeTest in the telemetry_perf_unittests step.

https://ci.chromium.org/buildbot/tryserver.chromium.android/android_n5x_swarming_rel/336788
https://ci.chromium.org/buildbot/tryserver.chromium.chromiumos/linux-chromeos-rel/34722
https://ci.chromium.org/buildbot/tryserver.chromium.linux/linux_chromium_rel_ng/620275
https://ci.chromium.org/buildbot/tryserver.chromium.win/win7_chromium_rel_ng/76819

Some background information about these benchmarks is at:
https://chromium.googlesource.com/chromium/src/+/master/docs/memory-infra/memory_benchmarks.md

This stacktrace looks relevant:

[3060:3180:0109/121159.627:FATAL:PaintLayer.h(338)] Check failed: !needs_descendant_dependent_flags_update_. 
  Backtrace:
  	base::debug::StackTrace::StackTrace [0x679F2D60+32]
  	base::debug::StackTrace::StackTrace [0x679EA12D+13]
  	logging::LogMessage::~LogMessage [0x6796F0F0+80]
  	blink::PaintLayer::HasVisibleContent [0x68B72153+85]
  	blink::LocalFrameView::InvalidateViewportConstrainedObjects [0x68C32835+551]
  	blink::PaintLayerScrollableArea::InvalidatePaintForScrollOffsetChange [0x68F7065B+321]
  	blink::PaintLayerScrollableArea::UpdateScrollOffset [0x68F701CF+427]
  	blink::ScrollableArea::ScrollOffsetChanged [0x69A9A783+153]
  	blink::ScrollableArea::SetScrollOffset [0x69A9A5C8+150]
  	blink::PaintLayerScrollableArea::ClampScrollOffsetAfterOverflowChange [0x68F7282F+85]
  	blink::LayoutView::UpdateAfterLayout [0x68E44377+27]
  	blink::LayoutBlock::SimplifiedLayout [0x68D9FD9F+275]
  	blink::LayoutBlockFlow::UpdateBlockLayout [0x68DA7D83+209]
  	blink::LayoutView::UpdateBlockLayout [0x68E42587+533]
  	blink::LayoutBlock::UpdateLayout [0x68D9F250+98]
  	blink::LayoutView::UpdateLayout [0x68E4276C+402]
  	blink::LocalFrameView::PerformLayout [0x68C3057A+528]
  	blink::LocalFrameView::UpdateLayout [0x68C2E98A+1736]
  	blink::Document::UpdateStyleAndLayout [0x69C5CA9E+262]
  	blink::Document::EnsurePaintLocationDataValidForNode [0x69C5CF27+109]
  	blink::Element::ClientQuads [0x69C79BD1+51]
  	blink::Element::getBoundingClientRect [0x69C79E84+52]
  	blink::V8Element::getBoundingClientRectMethodCallback [0x699B1877+95]
  	v8::internal::FunctionCallbackArguments::Call [0x66EECC0A+410]
  	v8::internal::Builtins::InvokeApiFunction [0x66FB0715+4421]
  	v8::internal::BuiltinArguments::BuiltinArguments [0x66FAF47E+494]
  	v8::internal::Builtin_HandleApiCall [0x66FAF0B1+161]