[Chromecast] Remove ChannelIDService for system url request context.
[Chromecast] Remove ChannelIDService for system url request context.

Not all the url requests made by the cast receiver use the system url
request context which had the channel ID service enabled (e.g. the
connectivity checker), so an incorrect session resumption would result
in SSL handshake failure. Since Cast receiver does not use channel ID
for client authentication, we should simply remove the service from the
url request context.

BUG=internal/24986939

Review URL: https://codereview.chromium.org/1404423004

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#354654}

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