Replace `is_chromecast` with `is_castos` and `is_cast_android` as appropriate. See linked bug for further context. Bug: chromium:1219802 Change-Id: If24af59e058940b7259cf4f1d9a3ba2ee0449cdb Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/265601 Reviewed-by: Henrik Andreassson <henrika@webrtc.org> Reviewed-by: David Dorwin <ddorwin@google.com> Reviewed-by: Mark Foltz <mfoltz@chromium.org> Commit-Queue: Ryan Keane <rwkeane@google.com> Cr-Commit-Position: refs/heads/main@{#37230}