Revert of Add TestMockTimeTaskRunner in base/test.

Revert of Add TestMockTimeTaskRunner in base/test. (patchset #5 id:100001 of https://codereview.chromium.org/823143004/)

Reason for revert:
Suspect that this patch broke the chromeos asan bots. It looks like all the AutomaticRebootManagerTestInstance/AutomaticRebootManagerTest tests now leak memory:

https://build.chromium.org/p/chromium.memory/builders/Linux%20Chromium%20OS%20ASan%20LSan%20Tests%20%281%29/builds/5799

Original issue's description:
> Add TestMockTimeTaskRunner in base/test.
>
> Multiple implementations of this functionality exist with slight modifications. This CL consolidates them.
>
> BUG=329911
> TBR=thestig@chromium.org  # For base/base.gyp changes.
>
> Committed: https://crrev.com/8d897fb17470c526155b2a9e86752be9a7f33c03
> Cr-Commit-Position: refs/heads/master@{#311091}

TBR=bartfab@chromium.org,phajdan.jr@chromium.org,stevenjb@chromium.org,thestig@chromium.org,engedy@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=329911
Committed: https://crrev.com/42f058496033336073d38ba0a1e36052d5b0475c
Cr-Commit-Position: refs/heads/master@{#311114}

[Elliot Glaysher, 2015-01-12 21:37:28]

Created Revert of Add TestMockTimeTaskRunner in base/test.

[commit-bot: I haz the power, 2015-01-12 21:37:49]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/844353002/1

[commit-bot: I haz the power, 2015-01-12 21:39:32]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-01-12 21:40:32]

Patchset 1 (id:??) landed as
https://crrev.com/42f058496033336073d38ba0a1e36052d5b0475c
Cr-Commit-Position: refs/heads/master@{#311114}