Fix missing ozone demo in CrOS build
Fix missing ozone demo in CrOS build

The ozone demo build file is currently removed from Chrome OS & chromecast
builds, but we want to have it in all builds that set use_ozone=true.

Review URL: https://codereview.chromium.org/1864583004

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#385462}

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