Introduce (Chrome)VariationsServiceClient

Introduce (Chrome)VariationsServiceClient

VariationsService is targeted for componentization in order to be shared with
iOS. Towards that goal, this CL introduces VariationsServiceClient, which will
serve to abstract the dependencies of VariationsService on its embedder (e.g.,
//chrome).

Future CLs will complete the abstraction of VariationsService's //chrome-level
dependencies through VariationsServiceClient.

BUG=516678
TBR=asvitkine

Committed: https://crrev.com/31f8bdbaac5826a596bc71dfb2b271715c85fcbe
Cr-Commit-Position: refs/heads/master@{#343857}

[blundell, 2015-08-17 15:53:50]

blundell@chromium.org changed reviewers:
+ stevet@chromium.org

[SteveT, 2015-08-17 15:58:36]

stevet@chromium.org changed reviewers:
+ asvitkine@google.com
- stevet@chromium.org

[SteveT, 2015-08-17 15:58:51]

stevet@chromium.org changed reviewers:
+ stevet@chromium.org

[SteveT, 2015-08-17 15:58:51]

Switching in Alexei as the reviewer as he is the proper owner of this now.

[blundell, 2015-08-17 16:00:25]

On 2015/08/17 15:58:51, SteveT wrote:
> Switching in Alexei as the reviewer as he is the proper owner of this now.

He's been doing my reviews so far, but is OOO this week; hence my turning to you
:). Are any of the other //chrome/browser/metrics OWNERS qualified here? This is
pretty straightforward refactoring work, and Alexei already approved the
high-level design. Thanks!

[SteveT, 2015-08-17 16:56:00]

OK if Alexei approved the high level changes then this LGTM from a C++-in-chrome
perspective.

Thanks!

[blundell, 2015-08-17 18:44:58]

The CQ bit was checked by blundell@chromium.org

[commit-bot: I haz the power, 2015-08-17 18:45:21]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1293113004/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1293113004/20001

[commit-bot: I haz the power, 2015-08-17 18:55:41]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-08-17 18:55:41]

Try jobs failed on following builders:
  chromium_presubmit on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/chromium_presub...)

[blundell, 2015-08-17 19:00:32]

TBR'ing Alexei for the addition of the new argument to VariationsService::Create
in //chrome/browser/metrics/metrics_services_manager.cc.

[blundell, 2015-08-17 19:00:38]

The CQ bit was checked by blundell@chromium.org

[commit-bot: I haz the power, 2015-08-17 19:01:21]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1293113004/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1293113004/20001

[commit-bot: I haz the power, 2015-08-17 21:20:23]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-08-17 21:20:23]

Try jobs failed on following builders:
  linux_chromium_rel_ng on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[blundell, 2015-08-17 21:36:47]

The CQ bit was checked by blundell@chromium.org

[commit-bot: I haz the power, 2015-08-17 21:37:22]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1293113004/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1293113004/20001

[commit-bot: I haz the power, 2015-08-18 00:09:49]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-08-18 00:09:49]

Try jobs failed on following builders:
  linux_chromium_rel_ng on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[blundell, 2015-08-18 07:44:20]

The CQ bit was checked by blundell@chromium.org

[commit-bot: I haz the power, 2015-08-18 07:44:28]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1293113004/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1293113004/20001

[commit-bot: I haz the power, 2015-08-18 08:15:07]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-08-18 08:15:41]

Patchset 2 (id:??) landed as
https://crrev.com/31f8bdbaac5826a596bc71dfb2b271715c85fcbe
Cr-Commit-Position: refs/heads/master@{#343857}