Remove unnecessary host parameter in forwarder.
Remove unnecessary host parameter in forwarder.

While it is nice to be able to specify the destination host when setting up a
redirection, this functionality is never used.
This cleanup is needed for some upcoming changes in forwarder2.

BUG=242846

Review URL: https://chromiumcodereview.appspot.com/18522003

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@209756 0039d316-1c4b-4281-b951-d872f2087c98

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