Please

On top of that:
 - UserClassifier should be injected into content_suggestions_service.
 - UserClassifier is created in a lot of tests, the code-duplication should be minimized.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/27b02c10c64ced00dc51231fb856d3d8c5afb33b

commit 27b02c10c64ced00dc51231fb856d3d8c5afb33b
Author: jkrcal <jkrcal@chromium.org>
Date: Tue Mar 21 11:18:26 2017

[UserClassifier] Inject a clock

This CL injects a clock into UserClassifier. This is a preparation work
before introducing a unit-test for UserClassifier.

BUG= 699027 

Review-Url: https://codereview.chromium.org/2759423003
Cr-Commit-Position: refs/heads/master@{#458373}

[modify] https://crrev.com/27b02c10c64ced00dc51231fb856d3d8c5afb33b/components/ntp_snippets/content_suggestions_service.cc
[modify] https://crrev.com/27b02c10c64ced00dc51231fb856d3d8c5afb33b/components/ntp_snippets/remote/remote_suggestions_fetcher_unittest.cc
[modify] https://crrev.com/27b02c10c64ced00dc51231fb856d3d8c5afb33b/components/ntp_snippets/remote/remote_suggestions_provider_impl_unittest.cc
[modify] https://crrev.com/27b02c10c64ced00dc51231fb856d3d8c5afb33b/components/ntp_snippets/remote/scheduling_remote_suggestions_provider_unittest.cc
[modify] https://crrev.com/27b02c10c64ced00dc51231fb856d3d8c5afb33b/components/ntp_snippets/user_classifier.cc
[modify] https://crrev.com/27b02c10c64ced00dc51231fb856d3d8c5afb33b/components/ntp_snippets/user_classifier.h

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/afbbf48b9c592f0e857bb5bba9179c925b24bf01

commit afbbf48b9c592f0e857bb5bba9179c925b24bf01
Author: jkrcal <jkrcal@chromium.org>
Date: Wed Mar 22 09:46:56 2017

[User classifier] Add a unit-test

This CL adds basic test support for UserClassifier. More advance tests
may follow.

BUG= 699027 

Review-Url: https://codereview.chromium.org/2761313002
Cr-Commit-Position: refs/heads/master@{#458701}

[modify] https://crrev.com/afbbf48b9c592f0e857bb5bba9179c925b24bf01/components/ntp_snippets/BUILD.gn
[add] https://crrev.com/afbbf48b9c592f0e857bb5bba9179c925b24bf01/components/ntp_snippets/user_classifier_unittest.cc

Most of the work is done. Decreasing the prio for further unit-tests and pushing them to M60.

Not important any more.