Fix build with GN arg enable_mojo_media=true.
Fix build with GN arg enable_mojo_media=true.

TBR=jam@chromium.org

Review URL: https://codereview.chromium.org/1770173002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#381259}

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