Revert of Use null rather than empty frame to lock Surface resources

Revert of Use null rather than empty frame to lock Surface resources (patchset #2 id:20001 of https://codereview.chromium.org/1073323002/)

Reason for revert:
This is causing timeouts on the gpu bots:
https://code.google.com/p/chromium/issues/detail?id=476544#c5

Original issue's description:
> Use null rather than empty frame to lock Surface resources
>
> This will allow the DisplayScheduler to differentiate between
> a frame without any resources and one that should not be drawn.
>
> Some tests use frames without any resources and the DisplayScheduler
> was missinterpreting that as the Browser locking resources.
>
> BUG=467750
>
> Committed: https://crrev.com/5e5956af406aec997246697735a11f4222d83bef
> Cr-Commit-Position: refs/heads/master@{#324765}

TBR=jbauman@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=467750
Committed: https://crrev.com/21df99ae0d91bcf2bc2deebef9cc0e850b27544e
Cr-Commit-Position: refs/heads/master@{#325100}

[brianderson, 2015-04-14 19:14:29]

Created Revert of Use null rather than empty frame to lock Surface resources

[commit-bot: I haz the power, 2015-04-14 19:15:08]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1088883004/1

[commit-bot: I haz the power, 2015-04-14 19:16:06]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-14 19:17:01]

Patchset 1 (id:??) landed as
https://crrev.com/21df99ae0d91bcf2bc2deebef9cc0e850b27544e
Cr-Commit-Position: refs/heads/master@{#325100}