DevTools: fix paint profiler in slimming paint mode

DevTools: fix paint profiler in slimming paint mode

Let Timeline extract recorded picture from cc::DisplayItemList in the same
way as it used to do with cc::Picture.

BUG=496779
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=196764

[caseq, 2015-06-08 17:20:29]

caseq@chromium.org changed reviewers:
+ pfeldman@chromium.org, yurys@chromium.org

[yurys, 2015-06-09 09:33:32]

lgtm

can we cover this with a test?

[caseq, 2015-06-09 09:39:20]

On 2015/06/09 09:33:32, yurys wrote:
> lgtm
> 
> can we cover this with a test?

See bug for details on test coverage (tl/dr: this is covered by existing test,
but it doesn't run on bots at the moment, will be run when slimming paint is
rolled out).

[caseq, 2015-06-09 09:39:27]

The CQ bit was checked by caseq@chromium.org

[commit-bot: I haz the power, 2015-06-09 09:39:41]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1149383009/1

[commit-bot: I haz the power, 2015-06-09 12:56:51]

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

[commit-bot: I haz the power, 2015-06-09 12:56:53]

Try jobs failed on following builders:
  win_blink_rel on tryserver.blink (JOB_FAILED,
http://build.chromium.org/p/tryserver.blink/builders/win_blink_rel/builds/65830)

[caseq, 2015-06-09 12:57:57]

The CQ bit was checked by caseq@chromium.org

[commit-bot: I haz the power, 2015-06-09 12:58:15]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1149383009/1

[commit-bot: I haz the power, 2015-06-09 13:48:41]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=196764