Add method to init HttpNetworkSession::Params from context bulder params

This method will most likely be temporary, and removed once IOThread's
and ProfileIOData's URLRequestContexts can be configured using a
URLRequestContextBuilder.

BUG=715697

Review-Url: https://codereview.chromium.org/2876243002
Cr-Commit-Position: refs/heads/master@{#471501}
2 files changed