Remove channel id binding from fetching uber tokens.

Support for channel ID binding was removed from Chrome a while back.
This CL removes some boolean that was referring to channel ID binding
from uber token fetcher.

Fixed: 1021455
Change-Id: I195056e7b3a2446afc1714c7394040b0171b6602
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1899851
Reviewed-by: David Roger <droger@chromium.org>
Reviewed-by: Ryan Sleevi <rsleevi@chromium.org>
Commit-Queue: Mihai Sardarescu <msarda@chromium.org>
Cr-Commit-Position: refs/heads/master@{#713775}
8 files changed