Make flow event traces disabled-by-default, and rename "ipc" and "task" categories to "toplevel"

Make flow event traces disabled-by-default

Currently all flow events are in the category "toplevel.flow", they originated from "ipc" and "task" categories.

BUG=338427
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=249450

[fmeawad, 2014-01-28 21:51:32]

A follow up CL will disable the check box in trace-viewer.
We also need to enable them for some telemetry analysis.
PTAL.

[nduca, 2014-01-28 22:57:34]

how about we make a category called toplevel == ipcs + posttasks and one called
DISABLED_BY_DEFAULT(toplevel.flow) == the flows for these.

toplevel is an idea that @epenner floated around that I think makes a lot of
sense. Hopefully its rather self explanatory what it means?

[nduca, 2014-01-29 01:08:26]

lgtm with toplevel as the new cateogry etc :)

[fmeawad, 2014-01-29 18:42:07]

PTAL.

[epennerAtGoogle, 2014-01-29 21:10:12]

On 2014/01/29 18:42:07, fmeawad-cr wrote:
> PTAL.

Thanks for doing this! FYI this is a significant improvement in noise for our
IPC thread measurements. This cuts off 0.6ms of 3.3ms we were measuring there.
Do you know the approx ratio of flow events that would be happening on an IPC
thread compared to other traces? There is two traces per IPC
(RunTask/DispatchMessage), so if there was also 2 flow events also, that means
the cost of a flow event was approximately ~0.015ms. If there was only one
io-thread flow event per IPC, the cost was ~0.03ms.

Regarding toplevel, I realized it's important that this only renames _actual_
top-level 'IPC'/'task' traces and not all of them (unless all of them are
actually truly top-level). Do you think that is the case for this patch?  The
problem I want to avoid is having some 'ipc'/'task' traces occurring on other
threads during dispatch of an IPC, but then having those show up (incorrectly)
in the 'top-level' category.

[jam, 2014-01-30 19:28:58]

ipc lgtm

[epenner, 2014-01-30 23:54:12]

On 2014/01/30 19:28:58, jam wrote:
> ipc lgtm

Lgtm.

We talked and I will verify top level labelling is 100% after this lands.

[fmeawad, 2014-02-04 18:21:06]

+Mark for base/debug base/message_loop

[Mark Mentovai, 2014-02-04 18:40:52]

LGTM

[fmeawad, 2014-02-04 18:44:42]

The CQ bit was checked by fmeawad@chromium.org

[commit-bot: I haz the power, 2014-02-04 18:49:06]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/fmeawad@chromium.org/148173011/50001

[commit-bot: I haz the power, 2014-02-04 21:14:35]

Retried try job too often on mac_rel for step(s) sync_integration_tests
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=mac_rel&nu...

[commit-bot: I haz the power, 2014-02-04 22:31:15]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/fmeawad@chromium.org/148173011/50001

[commit-bot: I haz the power, 2014-02-05 01:08:40]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/fmeawad@chromium.org/148173011/50001

[Paweł Hajdan Jr., 2014-02-05 19:51:06]

The CQ bit was unchecked by phajdan.jr@chromium.org

[Paweł Hajdan Jr., 2014-02-05 19:53:52]

The CQ bit was checked by phajdan.jr@chromium.org

[commit-bot: I haz the power, 2014-02-06 09:12:25]

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

[commit-bot: I haz the power, 2014-02-06 09:12:26]

List of reviewers changed. phajdan.jr@chromium.org did a drive-by without
LGTM'ing!

[fmeawad, 2014-02-06 18:21:40]

The CQ bit was checked by fmeawad@chromium.org

[commit-bot: I haz the power, 2014-02-06 18:23:34]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/fmeawad@chromium.org/148173011/50001

[commit-bot: I haz the power, 2014-02-06 18:28:56]

Change committed as 249450

[f(malita), 2014-02-06 23:07:34]

On 2014/02/06 18:28:56, I haz the power (commit-bot) wrote:
> Change committed as 249450

This is causing a Blink test to fail - see http://crbug.com/341641

[fmeawad, 2014-02-06 23:18:45]

A revert of this CL has been created in
https://codereview.chromium.org/133313005/ by fmeawad@chromium.org.

The reason for reverting is: This is causing a Blink test to fail - see
http://crbug.com/341641.