Revert of ui: Cache the output of View::OnPaint when the View isn't invalid.

Revert of ui: Cache the output of View::OnPaint when the View isn't invalid. (patchset #4 id:80001 of https://codereview.chromium.org/1101783002/)

Reason for revert:
ash_unittests are timing out on Win8 Aura and Linux ChromiumOS Tests (dbg)(1) bots.

Reverting this CL in order to revert https://codereview.chromium.org/1080633009/ which we suspect to be the cause of the problem.

Original issue's description:
> ui: Cache the output of View::OnPaint when the View isn't invalid.
>
> Store the output of View::OnPaint as a PaintCache object, and when the
> view has not been invalidated, use that cache output instead of doing
> work to build a recording.
>
> Performance data as follows when the loading spinner is going:
>
> Before impl-side (TOT): 0.13ms / paint
> With impl-side (no slimming paint): 0.22ms / paint
> With impl-side and slimming paint (this patch): 0.17ms / paint
>
> So this gets us some of the way there. I need to investigate why it's
> not doing more.
>
> R=piman@chromium.org, sky
> BUG=466426
>
> Committed: https://crrev.com/7f686cdcff81d6779b962e98e529a7360be2809c
> Cr-Commit-Position: refs/heads/master@{#326592}

TBR=piman@chromium.org,sky@chromium.org,danakj@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=466426
Committed: https://crrev.com/f2f043dcd893c280bbf8a2da9abf87c7abb50460
Cr-Commit-Position: refs/heads/master@{#326636}

[Justin Donnelly, 2015-04-23 20:50:55]

Created Revert of ui: Cache the output of View::OnPaint when the View isn't
invalid.

[commit-bot: I haz the power, 2015-04-23 20:51:43]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1108463002/1

[commit-bot: I haz the power, 2015-04-23 20:53:01]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-23 20:53:52]

Patchset 1 (id:??) landed as
https://crrev.com/f2f043dcd893c280bbf8a2da9abf87c7abb50460
Cr-Commit-Position: refs/heads/master@{#326636}