Cleanup arraysize usage in //net/base

When/where appropriate, the following conversions are made:
- Range based for-loops when iterating
- constexpr base::StringPiece for string constants
- [std::]begin() / [std::]end() when copying
- base::size() as last resort

Bug: 837308
Change-Id: I640ced508edb0b12f44534e0173a9d9402e627b6
Reviewed-on: https://chromium-review.googlesource.com/1043687
Commit-Queue: Ryan Sleevi <rsleevi@chromium.org>
Reviewed-by: David Benjamin <davidben@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#557554}
27 files changed