Revert of Revert of Unflake V8 sampling profiler tests.

Revert of Revert of Unflake V8 sampling profiler tests. (patchset #1 id:1 of https://codereview.chromium.org/1017183004/)

Reason for revert:
Suspecting goma flake. Relanding.

Original issue's description:
> Revert of Unflake V8 sampling profiler tests. (patchset #1 id:1 of https://codereview.chromium.org/1032633002/)
>
> Reason for revert:
> Broke compilation on Mac Builder:
> https://build.chromium.org/p/chromium.mac/builders/Mac%20Builder/builds/19512/steps/compile/logs/stdio
>
> when compiling content/renderer/devtools/v8_sampling_profiler_browsertest.cc
>
> Original issue's description:
> > Unflake V8 sampling profiler tests.
> >
> > BUG=406277
> >
> > Committed: https://crrev.com/d6493ce2a4ed6f346a31597ac27748a3429a1d95
> > Cr-Commit-Position: refs/heads/master@{#321970}
>
> TBR=yurys@chromium.org,alph@chromium.org
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=406277
>
> Committed: https://crrev.com/3703085199a63732add21d955c6280765e3c480e
> Cr-Commit-Position: refs/heads/master@{#321975}

TBR=yurys@chromium.org,pneubeck@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=406277
Committed: https://crrev.com/84fec4265a487f13b3edac5770b4ca02df95466a
Cr-Commit-Position: refs/heads/master@{#321977}

[alph, 2015-03-24 12:14:49]

Created Revert of Revert of Unflake V8 sampling profiler tests.

[commit-bot: I haz the power, 2015-03-24 12:14:56]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1029353002/1

[commit-bot: I haz the power, 2015-03-24 12:15:21]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-24 12:16:20]

Patchset 1 (id:??) landed as
https://crrev.com/84fec4265a487f13b3edac5770b4ca02df95466a
Cr-Commit-Position: refs/heads/master@{#321977}