Adding instrumentation to locate the source of jankiness.

Adding instrumentation to locate the source of jankiness.

Previous instrumentations showed that SSLClientSocketNSS::Core::DoHandshake alone is responsible for 14.4 janks per hour in IO thread. I need to instrument the code inside it to find out which part causes jank.

This is a mechanical change that adds instrumentation required to locate the source of jankiness (i.e. a long-running fragment of code executed as a part of the task that causes jank) in the code. See the bug for details on what kind of jank we are after.
A number of similar CLs were landed, and none of them caused issues. They've helped to find and fix janky code. The code of the instrumentation is highly optimized and is not expected to affect performance. The code simply creates a diagnostic task which is identical to ones created by PostTask or IPC message handlers.

BUG=424386
Committed: https://crrev.com/eeee2a4ce82edc3a0db3fd6b39c5891567216ef6
Cr-Commit-Position: refs/heads/master@{#302665}

[vadimt, 2014-10-28 22:28:02]

vadimt@chromium.org changed reviewers:
+ asanka@chromium.org

[vadimt, 2014-10-28 22:28:03]

asanka@, please provide OWNER's approval.

Note that I used to land similar CLs as TBRs until I was pointed out that such
changes don't qualify for TBR.

[asanka, 2014-10-31 18:22:32]

asanka@chromium.org changed reviewers:
+ davidben@chromium.org

[asanka, 2014-10-31 18:22:32]

+davidben FHI

I'm guessing we are using running Core in single-threaded mode (based on the
comment in code and the issue description)? The comment also suggests that the
possibility of jank is known for the single-threaded case.

[vadimt, 2014-11-04 03:01:47]

Hi!

Should I land this as is, or we are waiting for ideas regarding what else to
instrument?

[davidben, 2014-11-04 19:28:58]

lgtm.  Though note that this file is expected not to be used on Windows for M41.
(Current target release for switching Windows for BoringSSL.) And then we'll
have completely different sources of jank. :-)

On 2014/10/31 18:22:32, asanka wrote:
> +davidben FHI
> 
> I'm guessing we are using running Core in single-threaded mode (based on the
> comment in code and the issue description)? The comment also suggests that the
> possibility of jank is known for the single-threaded case.

If this is Windows then, yeah, this is single-threaded mode.

[vadimt, 2014-11-04 19:36:04]

Thanks!

I'm still landing the changes, at least to rule out other theories regarding the
source of the jank.

[vadimt, 2014-11-04 19:36:09]

The CQ bit was checked by vadimt@chromium.org

[commit-bot: I haz the power, 2014-11-04 19:37:47]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/687843002/1

[commit-bot: I haz the power, 2014-11-04 21:04:17]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-11-04 21:05:31]

Patchset 1 (id:??) landed as
https://crrev.com/eeee2a4ce82edc3a0db3fd6b39c5891567216ef6
Cr-Commit-Position: refs/heads/master@{#302665}