Move //base mojo types out of services/network

Follow up to http://crrev.com/c/1388036, this moves //base typemaps into
//mojo/public/cpp/base instead of living in services/network.

Bug: 917182
Change-Id: Ib306295b143923163c0ee3f77ab1586795a68966
Reviewed-on: https://chromium-review.googlesource.com/c/1399290
Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: Clark DuVall <cduvall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#620835}
18 files changed