Fix sampling of V8.DetachedContextAgeInGC histogram.

Fix sampling of V8.DetachedContextAgeInGC histogram.

BUG=

Committed: https://crrev.com/161161900befb8f4447e6d76a19fa9e924314143
Cr-Commit-Position: refs/heads/master@{#26719}

[ulan, 2015-02-18 13:14:32]

ulan@chromium.org changed reviewers:
+ hpayer@chromium.org

[ulan, 2015-02-18 13:14:33]

PTAL

https://codereview.chromium.org/938693002/diff/1/src/isolate.cc
File src/isolate.cc (left):

https://codereview.chromium.org/938693002/diff/1/src/isolate.cc#oldcode2602
src/isolate.cc:2602:
counters()->detached_context_age_in_gc()->AddSample(mark_sweeps);
We need to sample all detached contexts, not only the collected ones because if
there is a memory leak then the leaked context will never be collected.

[Hannes Payer (out of office), 2015-02-18 13:27:17]

LGTM

[ulan, 2015-02-18 13:29:02]

The CQ bit was checked by ulan@chromium.org

[commit-bot: I haz the power, 2015-02-18 13:29:15]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/938693002/1

[commit-bot: I haz the power, 2015-02-18 13:50:46]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-02-18 13:51:10]

Patchset 1 (id:??) landed as
https://crrev.com/161161900befb8f4447e6d76a19fa9e924314143
Cr-Commit-Position: refs/heads/master@{#26719}