[Chromecast] Remove resource tracker delegate check
[Chromecast] Remove resource tracker delegate check

This fires when the delegate tries to remove itself.  Just remove,
not convinced it's that useful.

BUG=

Review URL: https://codereview.chromium.org/1832043002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#383278}

axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk