What are any reason why this should be merged weeks after branch point?

Ah, I believe the code reviewer for Cathy's Impl CL gave the LGTM a day after branch point. We should have surfaced the merge request much earlier so many apologies for that. Our justification is that it is a relatively small change (just changing the look of the button) on a single net error page to help understand user behavior. This will shape some of the net errors work we have slated for M69, so having the information from the experiment sooner rather than later will be instrumental in helping us shape some of the product decisions. This isn't particularly critical (not fixing a regression), so I completely understand if this can't be merged. We'll ensure that we don't surface late merge requests in the future. 

This bug requires manual review: M67 has already been promoted to the beta branch, so this requires manual review
Please contact the milestone owner if you have questions.
Owners: cmasso@(Android), cmasso@(iOS), kbleicher@(ChromeOS), govind@(Desktop)

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

Approving this time in the hope that you do things better next time.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/f8ce8b7fdca25ce71e108816bd058a1d77a9dc66

commit f8ce8b7fdca25ce71e108816bd058a1d77a9dc66
Author: Cathy Li <chili@chromium.org>
Date: Tue May 01 19:58:12 2018

[Offline pages]: Show a different set of download button sets and styles based on experiment flag.

Bug:  836968 
Change-Id: I1aacf702cc4b2247179c97ab393f141090cd8940
Reviewed-on: https://chromium-review.googlesource.com/1009484
Commit-Queue: Cathy Li <chili@chromium.org>
Reviewed-by: Peter Williamson <petewil@chromium.org>
Reviewed-by: Matt Menke <mmenke@chromium.org>
Reviewed-by: Colin Blundell <blundell@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#551541}(cherry picked from commit 992fabdc0717d55b6eca5ba9f3a135ce90a86351)
Reviewed-on: https://chromium-review.googlesource.com/1028496
Reviewed-by: Cathy Li <chili@chromium.org>
Cr-Commit-Position: refs/branch-heads/3396@{#422}
Cr-Branched-From: 9ef2aa869bc7bc0c089e255d698cca6e47d6b038-refs/heads/master@{#550428}
[modify] https://crrev.com/f8ce8b7fdca25ce71e108816bd058a1d77a9dc66/components/error_page/common/localized_error.cc
[modify] https://crrev.com/f8ce8b7fdca25ce71e108816bd058a1d77a9dc66/components/neterror/resources/neterror.css
[modify] https://crrev.com/f8ce8b7fdca25ce71e108816bd058a1d77a9dc66/components/neterror/resources/neterror.js
[add] https://crrev.com/f8ce8b7fdca25ce71e108816bd058a1d77a9dc66/components/resources/default_100_percent/neterror/download_blue.png
[add] https://crrev.com/f8ce8b7fdca25ce71e108816bd058a1d77a9dc66/components/resources/default_100_percent/neterror/download_grey.png
[add] https://crrev.com/f8ce8b7fdca25ce71e108816bd058a1d77a9dc66/components/resources/default_200_percent/neterror/download_blue.png
[add] https://crrev.com/f8ce8b7fdca25ce71e108816bd058a1d77a9dc66/components/resources/default_200_percent/neterror/download_grey.png