So definitely backup-and-restore. Rob doesn't see a "EulaAccepted": true pref in chrome://local-state and also separately the code that's supposed to fetch a variations seed during backup-and-restore presumably didn't execute successfully. :(

So my changes from before should have the effect that if either the native or Java pref for ToS-Accepted (eula) is set, the other one also gets set:
https://codereview.chromium.org/2614183002
https://codereview.chromium.org/2621413008

As well as the Java pref being whitelisted for B&R.

Given the issue is still seen, it seems in this case neither of the prefs is set. However, we're still skipping first run. So maybe the solution is to mark both of those prefs as set if prefs indicate we shouldn't go through first run.

I'll give that a shot.

(Separately, there's a question of why the B&R variations seed fetching code didn't work here.)

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/2b81404991f0e44b9e87da014094819ca6dc1d08

commit 2b81404991f0e44b9e87da014094819ca6dc1d08
Author: asvitkine <asvitkine@chromium.org>
Date: Tue Apr 04 22:59:28 2017

Fix broken variations fetching on Android due to ToS pref.

In some cases, we've observed the ToS prefs to not be set at all
after a backup and restore scenario, yet with the FRE not being
shown. This CL attempts to fix those by ensure ToS prefs are set
if FRE is marked as completed.

BUG= 708302 

Review-Url: https://codereview.chromium.org/2803473002
Cr-Commit-Position: refs/heads/master@{#461880}

[modify] https://crrev.com/2b81404991f0e44b9e87da014094819ca6dc1d08/chrome/android/java/src/org/chromium/chrome/browser/firstrun/FirstRunGlueImpl.java

Requesting merge to M58.

Rob confirmed on his canary that this fixed his canary's ability to fetch experiments.

woot thanks! =)

Your change meets the bar and is auto-approved for M58. Please go ahead and merge the CL to branch 3029 manually. Please contact milestone owner if you have questions.
Owners: amineer@(Android), cmasso@(iOS), bhthompson@(ChromeOS), govind@(Desktop)

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

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d05425a9e6543d748ecd61d91c6a36ada225f06c

commit d05425a9e6543d748ecd61d91c6a36ada225f06c
Author: Alexei Svitkine <asvitkine@chromium.org>
Date: Wed Apr 05 17:51:09 2017

Fix broken variations fetching on Android due to ToS pref.

In some cases, we've observed the ToS prefs to not be set at all
after a backup and restore scenario, yet with the FRE not being
shown. This CL attempts to fix those by ensure ToS prefs are set
if FRE is marked as completed.

BUG= 708302 

Review-Url: https://codereview.chromium.org/2803473002
Cr-Commit-Position: refs/heads/master@{#461880}
(cherry picked from commit 2b81404991f0e44b9e87da014094819ca6dc1d08)

Review-Url: https://codereview.chromium.org/2802603004 .
Cr-Commit-Position: refs/branch-heads/3029@{#590}
Cr-Branched-From: 939b32ee5ba05c396eef3fd992822fcca9a2e262-refs/heads/master@{#454471}

[modify] https://crrev.com/d05425a9e6543d748ecd61d91c6a36ada225f06c/chrome/android/java/src/org/chromium/chrome/browser/firstrun/FirstRunGlueImpl.java

Marking as Fixed for M58.