[Oilpan] Count all GC marking events in tests

Changed to check if either precise GC or conservative GC events
run in tests.

Updating Oilpan's infrastructure, its behavior may change.
We expect that a GC runs in this test, but we cannot promise that
it is a precise GC.

Background:
We expected precise GC ran in those tests, but at some point,
they changed to call conservative GCs.

BUG=446301
TEST=./tools/perf/run_tests --browser=content-shell-release OilpanGCTimesTest

Committed: https://crrev.com/c326dd5aa4f62e44e97350248dbb1ebaf684af68
Cr-Commit-Position: refs/heads/master@{#310111}

[peria, 2015-01-06 06:28:22]

peria@chromium.org changed reviewers:
+ kouhei@chromium.org, oilpan-reviews@chromium.org, tonyg@chromium.org

[peria, 2015-01-06 06:28:23]

PTL

After this CL is landed, I will re-enable oilpan performance tests.

[kouhei (in TOK), 2015-01-06 06:32:44]

On 2015/01/06 06:28:23, peria wrote:
> PTL
> 
> After this CL is landed, I will re-enable oilpan performance tests.
lgtm

[haraken, 2015-01-06 06:39:27]

LGTM, thanks for the fix.

[tonyg, 2015-01-06 16:47:05]

The CQ bit was checked by tonyg@chromium.org

[tonyg, 2015-01-06 16:47:06]

lgtm

[commit-bot: I haz the power, 2015-01-06 16:47:29]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/818653004/1

[commit-bot: I haz the power, 2015-01-06 18:15:15]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-01-06 18:16:55]

Patchset 1 (id:??) landed as
https://crrev.com/c326dd5aa4f62e44e97350248dbb1ebaf684af68
Cr-Commit-Position: refs/heads/master@{#310111}