cc :: Fix mixmatch of Layer and LayerImpl ids in unit test.
cc :: Fix mixmatch of Layer and LayerImpl ids in unit test.

Ids of Layer and corresponding LayerImpl created in
LayerTest.LayerPropertyChangedForSubtree don't match. This CL
fixes that.

BUG=587587
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Review URL: https://codereview.chromium.org/1708833002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#376009}

axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk