The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/1de0fc2dd4e605249221cc8cd11350711a71c1c4

commit 1de0fc2dd4e605249221cc8cd11350711a71c1c4
Author: Jian Li <jianli@chromium.org>
Date: Thu Oct 12 00:18:32 2017

Update MHTML headers introduced to support sharing

Based on the feedback, we're going to update these headers as:
1) Remove X-Snapshot-Version header because the presence of a
Snapshot-Content-Location header is good enough to identify
the new behavior.
2) Drop X- prefix from X-Snapshot-Content-Location header since
the prefix is not encouraged per
https://tools.ietf.org/html/rfc6648.
3) Make Subject support RFC 2047 which can encode non-printable
ASCII

Bug:  771821 
Change-Id: I99a76f6f954848d59c33caad7e79ff8d9a50e1ba
Reviewed-on: https://chromium-review.googlesource.com/701262
Reviewed-by: Chris Harrelson <chrishtr@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: Jian Li <jianli@chromium.org>
Cr-Commit-Position: refs/heads/master@{#508189}
[modify] https://crrev.com/1de0fc2dd4e605249221cc8cd11350711a71c1c4/third_party/WebKit/Source/core/frame/MHTMLTest.cpp
[modify] https://crrev.com/1de0fc2dd4e605249221cc8cd11350711a71c1c4/third_party/WebKit/Source/platform/mhtml/MHTMLArchive.cpp