Refactor fake Connection subclasses in proximity_auth/ tests to a single file.

Refactor fake Connection subclasses in proximity_auth/ tests to a single file.

BUG=527558
TEST=existing unit tests pass

Committed: https://crrev.com/61a7c102df4f46e561bfca99f1f5989bb651476f
Cr-Commit-Position: refs/heads/master@{#350696}

[Tim Song, 2015-09-16 18:27:41]

tengs@chromium.org changed reviewers:
+ sacomoto@chromium.org

[sacomoto, 2015-09-18 15:45:21]

LGTM.

[Tim Song, 2015-09-24 20:42:31]

The CQ bit was checked by tengs@chromium.org

[Tim Song, 2015-09-24 20:42:32]

The patchset sent to the CQ was uploaded after l-g-t-m from
sacomoto@chromium.org
Link to the patchset: https://codereview.chromium.org/1351473003/#ps40001
(title: "rebase")

[commit-bot: I haz the power, 2015-09-24 20:43:42]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1351473003/40001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1351473003/40001

[commit-bot: I haz the power, 2015-09-24 22:12:27]

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

[commit-bot: I haz the power, 2015-09-24 22:12:28]

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

[Tim Song, 2015-09-24 22:34:35]

The CQ bit was checked by tengs@chromium.org

[commit-bot: I haz the power, 2015-09-24 22:35:24]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1351473003/40001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1351473003/40001

[commit-bot: I haz the power, 2015-09-24 23:25:24]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2015-09-24 23:25:40]

Patchset 3 (id:??) landed as
https://crrev.com/61a7c102df4f46e561bfca99f1f5989bb651476f
Cr-Commit-Position: refs/heads/master@{#350696}