Revert of Revert of Add record-as-much-as-possible mode for about://tracing.

Revert of Revert of Add record-as-much-as-possible mode for about://tracing. (patchset #1 id:1 of https://codereview.chromium.org/1043973003/)

Reason for revert:
Size increase in https://code.google.com/p/chromium/issues/detail?id=471610 is WAI.

Original issue's description:
> Revert of Add record-as-much-as-possible mode for about://tracing. (patchset #1 id:1 of https://codereview.chromium.org/1033223008/)
>
> Reason for revert:
> Speculative revert to see if this cause 340kb increase in size (BUG=471610
)
>
> Original issue's description:
> > Add record-as-much-as-possible mode for about://tracing.
> >
> > Update DEPS for trace-viewer to include the 3 tracing modes selector.
> >
> > BUG=396081
> > TEST=
> >
> > Committed: https://crrev.com/8e752353b04c52cb3ba1d54b79fce241c0be53d3
> > Cr-Commit-Position: refs/heads/master@{#322689}
>
> TBR=nduca@chromium.org,nduca@google.com
>
> BUG=396081
>
> Committed: https://crrev.com/bd28da0bfa3c2105937e61c6fe806c7ba7d43f01
> Cr-Commit-Position: refs/heads/master@{#322853}

TBR=nduca@chromium.org,nduca@google.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=396081
Committed: https://crrev.com/78a183adc6ae3790c242ca1c2cdb39029cffd0c5
Cr-Commit-Position: refs/heads/master@{#322913}

[nednguyen, 2015-03-30 23:49:37]

Created Revert of Revert of Add record-as-much-as-possible mode for
about://tracing.

[commit-bot: I haz the power, 2015-03-30 23:50:21]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1045123003/1

[nednguyen, 2015-03-30 23:51:17]

The CQ bit was unchecked by nednguyen@google.com

[commit-bot: I haz the power, 2015-03-30 23:51:20]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-30 23:52:19]

Patchset 1 (id:??) landed as
https://crrev.com/78a183adc6ae3790c242ca1c2cdb39029cffd0c5
Cr-Commit-Position: refs/heads/master@{#322913}

[Nico, 2015-03-31 15:43:26]

thakis@chromium.org changed reviewers:
+ thakis@chromium.org

[Nico, 2015-03-31 15:43:26]

Why was this relanded? This adds 300 kB, this is not WAI. I'll revert this
again; please leave it out until this feature no longer adds 300 kB.

[Nico, 2015-03-31 15:43:54]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/1049283002/ by thakis@chromium.org.

The reason for reverting is: Still causes bloat (crbug.com/471610).