Added MockPresentationClient to use in layout tests.

Added MockPresentationClient to use in layout tests.

Blink change with the test follows: https://codereview.chromium.org/906673002/

BUG=412331
Committed: https://crrev.com/49a225f6ecb52b805a99d55e9e37ed7e21ef7c1b
Cr-Commit-Position: refs/heads/master@{#315204}

[whywhat, 2015-02-06 20:19:03]

avayvod@chromium.org changed reviewers:
+ mkwst@chromium.org, peter@chromium.org

[whywhat, 2015-02-06 20:19:21]

PTaL

[Mike West, 2015-02-07 04:36:41]

LGTM.

[whywhat, 2015-02-07 12:43:16]

The CQ bit was checked by avayvod@chromium.org

[commit-bot: I haz the power, 2015-02-07 12:44:05]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/905823004/1

[commit-bot: I haz the power, 2015-02-07 13:32:12]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-02-07 13:33:07]

Patchset 1 (id:??) landed as
https://crrev.com/49a225f6ecb52b805a99d55e9e37ed7e21ef7c1b
Cr-Commit-Position: refs/heads/master@{#315204}

[dsinclair, 2015-02-07 14:44:27]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/906753002/ by dsinclair@chromium.org.

The reason for reverting is: This is causing layout failures on the blink bots.
They're crashing with the following assertion:

STDERR:
[17800:1287:0207/062834:4514258387182:FATAL:mock_presentation_client.cc(34)]
Check failed: controller_ != controller && (!controller || !controller_). .