The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/platform2/+/e99fd4f0b1362027fc06946f51736a37e5eba2d4

commit e99fd4f0b1362027fc06946f51736a37e5eba2d4
Author: Allen Webb <allenwebb@google.com>
Date: Sat Dec 29 03:57:04 2018

system_api: Add IsFeatureEnabled dbus method in server_constants.h

This adds a dbus constant:
kChromeFeaturesServiceIsFeatureEnabledMethod
This represents a generic dbus function for querying if particular
feature flags are enabled to streamline the process of adding feature
flag checks in Chrome OS.

BUG= chromium:915754 
TEST=CL:1383057 compiles

Change-Id: I034cd49fc8b1730d4ae434871be8a38f192cc70d
Reviewed-on: https://chromium-review.googlesource.com/1380611
Commit-Ready: Allen Webb <allenwebb@google.com>
Tested-by: Allen Webb <allenwebb@google.com>
Reviewed-by: Allen Webb <allenwebb@google.com>

[modify] https://crrev.com/e99fd4f0b1362027fc06946f51736a37e5eba2d4/system_api/dbus/service_constants.h

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/0207eefb445f9855c2ed46280cb835b6f08bdb30

commit 0207eefb445f9855c2ed46280cb835b6f08bdb30
Author: Allen Webb <allenwebb@google.com>
Date: Mon Jan 14 22:34:01 2019

chrome_features_service_provider: Add IsFeatureEnabled D-Bus method.

This adds a generic function for querying if whitelisted feature flags
are enabled or disabled over D-Bus.

BUG= chromium:915754 

Change-Id: If84838e9d207c6beade846e99ae6bb8d021e47c4
Reviewed-on: https://chromium-review.googlesource.com/c/1383057
Commit-Queue: Allen Webb <allenwebb@google.com>
Reviewed-by: Mattias Nissler <mnissler@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#622637}
[modify] https://crrev.com/0207eefb445f9855c2ed46280cb835b6f08bdb30/chrome/browser/chromeos/dbus/chrome_features_service_provider.cc
[modify] https://crrev.com/0207eefb445f9855c2ed46280cb835b6f08bdb30/chrome/browser/chromeos/dbus/chrome_features_service_provider.h