I start to work on this issue since I didn't find any blocker on it.
Now the geolocation_context.mojom is already hosted by device service, geolocation_context owns the geolocation_impl.
So the risk/fingerprint can be converted as customer of geolocation_context. Note that fingerprint just wants to get the geo-position only once, so it don't need to setclient to geolocation-core, just call the QueryNextPosition() of geolocation.mojom is ok.

If my above understanding is correct, the 725065 is not really a blocker.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/aef0ac75e8be45fc95fdcae4562e115ce8d9b1cc

commit aef0ac75e8be45fc95fdcae4562e115ce8d9b1cc
Author: Ke He <ke.he@intel.com>
Date: Tue Nov 21 03:40:26 2017

Migrate components/autofill/content/browser/risk to consume geolocation via mojo

All clients of geolocation-core should be converted to consume via mojo.
Accordingly, in browsertest it shouldn't call the
OverrideLocationForTesting() either, instead, we use the
Connector::TestApi::OverrideBinderForTesting().

BUG= 725066 

Change-Id: I1cdeae60a3a08336a5ca12b044941d8347992dd7
Reviewed-on: https://chromium-review.googlesource.com/771380
Reviewed-by: Evan Stade <estade@chromium.org>
Reviewed-by: Tim Volodine <timvolodine@chromium.org>
Reviewed-by: Colin Blundell <blundell@chromium.org>
Commit-Queue: Ke He <ke.he@intel.com>
Cr-Commit-Position: refs/heads/master@{#518094}
[modify] https://crrev.com/aef0ac75e8be45fc95fdcae4562e115ce8d9b1cc/chrome/browser/autofill/risk_util.cc
[modify] https://crrev.com/aef0ac75e8be45fc95fdcae4562e115ce8d9b1cc/components/BUILD.gn
[modify] https://crrev.com/aef0ac75e8be45fc95fdcae4562e115ce8d9b1cc/components/autofill/content/browser/BUILD.gn
[modify] https://crrev.com/aef0ac75e8be45fc95fdcae4562e115ce8d9b1cc/components/autofill/content/browser/DEPS
[modify] https://crrev.com/aef0ac75e8be45fc95fdcae4562e115ce8d9b1cc/components/autofill/content/browser/risk/fingerprint.cc
[modify] https://crrev.com/aef0ac75e8be45fc95fdcae4562e115ce8d9b1cc/components/autofill/content/browser/risk/fingerprint.h
[modify] https://crrev.com/aef0ac75e8be45fc95fdcae4562e115ce8d9b1cc/components/autofill/content/browser/risk/fingerprint_browsertest.cc