Computer Configuration > Administrative Templates > Google Chrome > Google Cast
Both
HKLM\Software\Policies\Google\Chrome
When this policy is enabled, media playback controls UI is available for Google Cast sessions started by other devices on the local network. When this policy is unset for enterprise users or is disabled, media playback controls UI is unavailable for Google Cast sessions started by other devices on the local network. If the policy EnableMediaRouter is disabled, then this policy's value has no effect, as the entire Google Cast functionality is disabled.