Cleanup: Remove CancelationSignal from HttpBridgeFactory

Since crrev.com/c/1174655 landed (more than a year ago),
HttpBridgeFactory doesn't actually need the CancelationSignal anymore.
Removing it also lets us remove a bunch of plumbing.

Bug: 951350
Change-Id: Ic4332320845747aacae43bc7062094f6da77b13b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1912715
Commit-Queue: Marc Treib <treib@chromium.org>
Reviewed-by: Mikel Astiz <mastiz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#714921}
10 files changed