cc: Convert LTHCommon tests to LayerImpl
cc: Convert LTHCommon tests to LayerImpl

Converted these LayerTreeHostCommon tests:
    RenderSurfaceListForRenderSurfaceWithClippedLayer
    RenderSurfaceTransformsInHighDPI
    RenderSurfaceTransformsInHighDPIAccurateScaleZeroPosition

This lets them ask about render surface layer list sizes.  It's not that
critical to these tests, but arguably the main thread doesn't need to
know about screen space transforms either.

R=weiliangc@chromium.org
BUG=504466
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Review URL: https://codereview.chromium.org/1252263003

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#340483}

ltilve/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend