[AsyncFontAccess] Prewarm the default family for `<input>`

This patch prewarms the default font family for `<input
type="text">`.

This patch has no behavior changes because `PrewarmFamily` is
still no-op.

Bug: 1256946
Change-Id: If9735280f7d71b2aa0682208f5971edeaa3841c8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3226536
Reviewed-by: Kent Tamura <tkent@chromium.org>
Commit-Queue: Koji Ishii <kojii@chromium.org>
Cr-Commit-Position: refs/heads/main@{#932433}