This is because the account_hash was not encoded in 64. Since this is stored in JSON, it failed. Fixing it now.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/a37f19afa363b73c9af728e5bbff597763f0899b

commit a37f19afa363b73c9af728e5bbff597763f0899b
Author: sebsg <sebsg@chromium.org>
Date: Thu Dec 13 23:17:53 2018

[AF] Encode64 the account hash for the Wallet Sync Transport opt-in.

Bug:  914935 
Change-Id: I40c9f26a39db803d961f227e4dd8ec06ce3b2b6d
Reviewed-on: https://chromium-review.googlesource.com/c/1376810
Reviewed-by: David Benjamin <davidben@chromium.org>
Commit-Queue: Sebastien Seguin-Gagnon <sebsg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#616476}
[modify] https://crrev.com/a37f19afa363b73c9af728e5bbff597763f0899b/components/autofill/core/common/autofill_prefs.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d1491a466a56a8c0579b9840fdee32513c696977

commit d1491a466a56a8c0579b9840fdee32513c696977
Author: sebsg <sebsg@chromium.org>
Date: Fri Dec 14 18:21:43 2018

[AF] Add test for the Wallet Sync Transport opt-in pref serialization

Bug:  914935 
Change-Id: I52dde692e3f803cf5923090541371bec726667d5
Reviewed-on: https://chromium-review.googlesource.com/c/1378231
Reviewed-by: Tommy Martino <tmartino@chromium.org>
Commit-Queue: Sebastien Seguin-Gagnon <sebsg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#616749}
[modify] https://crrev.com/d1491a466a56a8c0579b9840fdee32513c696977/components/autofill/core/common/autofill_prefs_unittest.cc

Just a note that the merge is necessary only for the first CL. It's a 2-3 liner a very safe. I tested it extensively this morning

This bug requires manual review: M72 has already been promoted to the beta branch, so this requires manual review
Please contact the milestone owner if you have questions.
Owners: govind@(Android), kariahda@(iOS), djmm@(ChromeOS), abdulsyed@(Desktop)

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

I verified this fix in Canary this AM.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/b60e446ba5ce6d476f3fe2ef329f22854eaa0130

commit b60e446ba5ce6d476f3fe2ef329f22854eaa0130
Author: sebsg <sebsg@chromium.org>
Date: Mon Dec 17 17:55:03 2018

Merge72 [AF] Encode64 account hash for the Wallet Sync Transport opt-in.

TBR=sebsg@chromium.org

(cherry picked from commit a37f19afa363b73c9af728e5bbff597763f0899b)

Bug:  914935 
Change-Id: I40c9f26a39db803d961f227e4dd8ec06ce3b2b6d
Reviewed-on: https://chromium-review.googlesource.com/c/1376810
Reviewed-by: David Benjamin <davidben@chromium.org>
Commit-Queue: Sebastien Seguin-Gagnon <sebsg@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#616476}
Reviewed-on: https://chromium-review.googlesource.com/c/1380333
Reviewed-by: Sebastien Seguin-Gagnon <sebsg@chromium.org>
Cr-Commit-Position: refs/branch-heads/3626@{#388}
Cr-Branched-From: d897fb137fbaaa9355c0c93124cc048824eb1e65-refs/heads/master@{#612437}
[modify] https://crrev.com/b60e446ba5ce6d476f3fe2ef329f22854eaa0130/components/autofill/core/common/autofill_prefs.cc

The following revision refers to this bug: 
https://chromium.googlesource.com/chromium/src.git/+/b60e446ba5ce6d476f3fe2ef329f22854eaa0130

Commit: b60e446ba5ce6d476f3fe2ef329f22854eaa0130
Author: sebsg@chromium.org
Commiter: sebsg@chromium.org
Date: 2018-12-17 17:55:03 +0000 UTC

Merge72 [AF] Encode64 account hash for the Wallet Sync Transport opt-in.

TBR=sebsg@chromium.org

(cherry picked from commit a37f19afa363b73c9af728e5bbff597763f0899b)

Bug:  914935 
Change-Id: I40c9f26a39db803d961f227e4dd8ec06ce3b2b6d
Reviewed-on: https://chromium-review.googlesource.com/c/1376810
Reviewed-by: David Benjamin <davidben@chromium.org>
Commit-Queue: Sebastien Seguin-Gagnon <sebsg@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#616476}
Reviewed-on: https://chromium-review.googlesource.com/c/1380333
Reviewed-by: Sebastien Seguin-Gagnon <sebsg@chromium.org>
Cr-Commit-Position: refs/branch-heads/3626@{#388}
Cr-Branched-From: d897fb137fbaaa9355c0c93124cc048824eb1e65-refs/heads/master@{#612437}