[tracing] Add test for memory-infra startup tracing

[tracing] Add test for memory-infra startup tracing

This is a follow-up to crrev.com/1333873002 that introduced
support to startup tracing.
Also this change refactors the TraceConfig JSON used by
various memory-infra tests (in and out of base) into a
test_util.h file.
Furthermore this change fixes a off-by-one mistake in the
periodic scheduler (and its test).

BUG=524057
Committed: https://crrev.com/26b6f415865b7eab46b099d5773fbc0cb9e98b77
Cr-Commit-Position: refs/heads/master@{#348373}

[Primiano Tucci (use gerrit), 2015-09-10 16:08:27]

primiano@chromium.org changed reviewers:
+ dsinclair@chromium.org, zhenw@chromium.org

[Primiano Tucci (use gerrit), 2015-09-10 16:09:07]

+dsinclair
zhenw, mind if do some very small refactoring in trace_config_unittest? I need
those memory-infra strings also outside.

[dsinclair, 2015-09-10 16:43:46]

lgtm w/ nit.

https://codereview.chromium.org/1335503003/diff/40001/base/trace_event/memory...
File base/trace_event/memory_dump_manager_unittest.cc (right):

https://codereview.chromium.org/1335503003/diff/40001/base/trace_event/memory...
base/trace_event/memory_dump_manager_unittest.cc:587: // being, it will still
late-join the party (real use case: startup tracing).
nit: s/did already being/already began

[Primiano Tucci (use gerrit), 2015-09-10 17:01:24]

https://codereview.chromium.org/1335503003/diff/40001/base/trace_event/memory...
File base/trace_event/memory_dump_manager_unittest.cc (right):

https://codereview.chromium.org/1335503003/diff/40001/base/trace_event/memory...
base/trace_event/memory_dump_manager_unittest.cc:587: // being, it will still
late-join the party (real use case: startup tracing).
On 2015/09/10 16:43:46, dsinclair wrote:
> nit: s/did already being/already began

Done.

[Primiano Tucci (use gerrit), 2015-09-11 09:49:21]

The CQ bit was checked by primiano@chromium.org

[Primiano Tucci (use gerrit), 2015-09-11 09:49:21]

The patchset sent to the CQ was uploaded after l-g-t-m from
dsinclair@chromium.org
Link to the patchset: https://codereview.chromium.org/1335503003/#ps60001
(title: "Nit")

[commit-bot: I haz the power, 2015-09-11 09:49:25]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1335503003/60001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1335503003/60001

[commit-bot: I haz the power, 2015-09-11 11:04:51]

Committed patchset #4 (id:60001)

[commit-bot: I haz the power, 2015-09-11 11:05:31]

Patchset 4 (id:??) landed as
https://crrev.com/26b6f415865b7eab46b099d5773fbc0cb9e98b77
Cr-Commit-Position: refs/heads/master@{#348373}

[commit-bot: I haz the power, 2015-09-23 12:21:11]

Patchset 4 (id:??) landed as
https://crrev.com/26b6f415865b7eab46b099d5773fbc0cb9e98b77
Cr-Commit-Position: refs/heads/master@{#348373}