Reland of "[heap] Tracer: Handle incremental marking scopes"

[heap] Tracer: Handle incremental marking scopes

Before this patch all tracing scopes in incremental marking would be reset
during a gc tracer start/stop cycle. This patch handles scopes the same way it
does other incremental marking metrics.

Also:
- Align finalization metric with regular marking metric.
- Smaller cleanups

BUG=chromium:639818
Committed: https://crrev.com/7695642e2c7d893d300920ac0084905288f72859
Cr-Commit-Position: refs/heads/master@{#38834}

[Michael Lippautz, 2016-08-23 14:32:39]

Description was changed from

==========
Reland of "[heap] Tracer: Handle incremental marking scopes"

BUG=chromium:639818
==========

to

==========
[heap] Tracer: Handle incremental marking scopes

Before this patch all tracing scopes in incremental marking would be reset
during a gc tracer start/stop cycle. This patch handles scopes the same way it
does other incremental marking metrics.

Also:
- Align finalization metric with regular marking metric.
- Smaller cleanups

BUG=chromium:639818
==========

[Michael Lippautz, 2016-08-23 14:37:59]

The CQ bit was checked by mlippautz@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-08-23 14:38:08]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[Michael Lippautz, 2016-08-23 14:51:07]

mlippautz@chromium.org changed reviewers:
+ jochen@chromium.org

[jochen (gone - plz use gerrit), 2016-08-23 14:52:14]

lgtm

[commit-bot: I haz the power, 2016-08-23 15:11:06]

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

[commit-bot: I haz the power, 2016-08-23 15:11:06]

Dry run: This issue passed the CQ dry run.

[Michael Lippautz, 2016-08-23 15:11:20]

The CQ bit was checked by mlippautz@chromium.org

[commit-bot: I haz the power, 2016-08-23 15:11:26]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-08-23 15:13:28]

Description was changed from

==========
[heap] Tracer: Handle incremental marking scopes

Before this patch all tracing scopes in incremental marking would be reset
during a gc tracer start/stop cycle. This patch handles scopes the same way it
does other incremental marking metrics.

Also:
- Align finalization metric with regular marking metric.
- Smaller cleanups

BUG=chromium:639818
==========

to

==========
[heap] Tracer: Handle incremental marking scopes

Before this patch all tracing scopes in incremental marking would be reset
during a gc tracer start/stop cycle. This patch handles scopes the same way it
does other incremental marking metrics.

Also:
- Align finalization metric with regular marking metric.
- Smaller cleanups

BUG=chromium:639818
==========

[commit-bot: I haz the power, 2016-08-23 15:13:29]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2016-08-23 15:14:08]

Description was changed from

==========
[heap] Tracer: Handle incremental marking scopes

Before this patch all tracing scopes in incremental marking would be reset
during a gc tracer start/stop cycle. This patch handles scopes the same way it
does other incremental marking metrics.

Also:
- Align finalization metric with regular marking metric.
- Smaller cleanups

BUG=chromium:639818
==========

to

==========
[heap] Tracer: Handle incremental marking scopes

Before this patch all tracing scopes in incremental marking would be reset
during a gc tracer start/stop cycle. This patch handles scopes the same way it
does other incremental marking metrics.

Also:
- Align finalization metric with regular marking metric.
- Smaller cleanups

BUG=chromium:639818

Committed: https://crrev.com/7695642e2c7d893d300920ac0084905288f72859
Cr-Commit-Position: refs/heads/master@{#38834}
==========

[commit-bot: I haz the power, 2016-08-23 15:14:08]

Patchset 3 (id:??) landed as
https://crrev.com/7695642e2c7d893d300920ac0084905288f72859
Cr-Commit-Position: refs/heads/master@{#38834}