Taking this, as I'm looking into a probable duplicate (issue 796814)

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/1324ea47d5870af00fccd488d06bb1bf68d00947

commit 1324ea47d5870af00fccd488d06bb1bf68d00947
Author: Toni Barzic <tbarzic@google.com>
Date: Sat Jan 27 02:25:21 2018

Updates preference.onPrefChaged dispatch to split incognito profile

Fixes two issues with how incognito extension prefs changes are
dispatched when the extension is in split incognito mode:
 1. If an extension was incognito split, but not incognito enabled, the
    incognito prefs changes were dispatched to the the extension's
    original profile instance (even though extension in the original
    profile generally cannot access incognito prefs). This CL does not
    dispatch incognito pref changes to extensions that are not
    incognito enabled.
 2. If an incognito pref change was dispatched to an incognito split
    extension when OTR profile was not around, in order to restrict
    the preference to the OTR profile, DispatchEventToExtensions()
    function would call Profile::GetOffTheRecordProfile which would
    create an OTR profile instance. This cl avoids this issue by
    dropping  the events that are expected to be restricted to a
    non-existent OTR profiles
    (Note: if the pref value changed in the original profile, and there
     is no incognito specific pref value, the value change is reported
     for the incognito pref, too),

BUG=796814, 805480 

Change-Id: I093949c9f9123e3baaab56932903f4f2be55903c
Reviewed-on: https://chromium-review.googlesource.com/882508
Commit-Queue: Toni Barzic <tbarzic@chromium.org>
Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#532128}
[modify] https://crrev.com/1324ea47d5870af00fccd488d06bb1bf68d00947/chrome/browser/extensions/api/preference/preference_apitest.cc
[modify] https://crrev.com/1324ea47d5870af00fccd488d06bb1bf68d00947/chrome/browser/extensions/api/preference/preference_helpers.cc
[add] https://crrev.com/1324ea47d5870af00fccd488d06bb1bf68d00947/chrome/test/data/extensions/api_test/preference/onchange_split_regular_only/manifest.json
[add] https://crrev.com/1324ea47d5870af00fccd488d06bb1bf68d00947/chrome/test/data/extensions/api_test/preference/onchange_split_regular_only/test.js

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/39d21bd986d55d316f8374ad7d6a5667f817885f

commit 39d21bd986d55d316f8374ad7d6a5667f817885f
Author: Toni Barzic <tbarzic@google.com>
Date: Thu Feb 01 03:47:49 2018

Merge: Updates preference.onPrefChaged dispatch to split incognito profile

Fixes two issues with how incognito extension prefs changes are
dispatched when the extension is in split incognito mode:
 1. If an extension was incognito split, but not incognito enabled, the
    incognito prefs changes were dispatched to the the extension's
    original profile instance (even though extension in the original
    profile generally cannot access incognito prefs). This CL does not
    dispatch incognito pref changes to extensions that are not
    incognito enabled.
 2. If an incognito pref change was dispatched to an incognito split
    extension when OTR profile was not around, in order to restrict
    the preference to the OTR profile, DispatchEventToExtensions()
    function would call Profile::GetOffTheRecordProfile which would
    create an OTR profile instance. This cl avoids this issue by
    dropping  the events that are expected to be restricted to a
    non-existent OTR profiles
    (Note: if the pref value changed in the original profile, and there
     is no incognito specific pref value, the value change is reported
     for the incognito pref, too),

BUG=796814, 805480 
TBR=tbarzic@google.com

(cherry picked from commit 1324ea47d5870af00fccd488d06bb1bf68d00947)

Change-Id: I093949c9f9123e3baaab56932903f4f2be55903c
Reviewed-on: https://chromium-review.googlesource.com/882508
Commit-Queue: Toni Barzic <tbarzic@chromium.org>
Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#532128}
Reviewed-on: https://chromium-review.googlesource.com/896864
Reviewed-by: Toni Barzic <tbarzic@chromium.org>
Cr-Commit-Position: refs/branch-heads/3325@{#226}
Cr-Branched-From: bc084a8b5afa3744a74927344e304c02ae54189f-refs/heads/master@{#530369}
[modify] https://crrev.com/39d21bd986d55d316f8374ad7d6a5667f817885f/chrome/browser/extensions/api/preference/preference_apitest.cc
[modify] https://crrev.com/39d21bd986d55d316f8374ad7d6a5667f817885f/chrome/browser/extensions/api/preference/preference_helpers.cc
[add] https://crrev.com/39d21bd986d55d316f8374ad7d6a5667f817885f/chrome/test/data/extensions/api_test/preference/onchange_split_regular_only/manifest.json
[add] https://crrev.com/39d21bd986d55d316f8374ad7d6a5667f817885f/chrome/test/data/extensions/api_test/preference/onchange_split_regular_only/test.js