[FCP++] Test: track background image and layout image individually

This CL is to add a test to verify that background image and layout
image are tracked individually.

Bug: 943205
Change-Id: I41f0ba071643e31c3f1a67af4601ac5e37adfcb9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1579468
Reviewed-by: Steve Kobes <skobes@chromium.org>
Commit-Queue: Liquan (Max) Gu <maxlg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#654238}
1 file changed