Remove typically unused local_metadata_ field.

Remove typically unused local_metadata_ field.

The vast majority of histograms and their samples are now "persistent"
with the memory coming from a special memory segment. It's wasteful to
have a "local metadata" structure in each sample object that is never
used.

Instead, allocate the structure from the heap for only those objects
that need it and release it when those objects get destructed.

BUG=733380
Review-Url: https://codereview.chromium.org/2973603002
Cr-Commit-Position: refs/heads/master@{#484282}
Committed: https://chromium.googlesource.com/chromium/src/+/b4d87bb384bfc8b43cadc24160c0da01ab09f555

[bcwhite, 2017-07-05 12:58:08]

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

[commit-bot: I haz the power, 2017-07-05 12:58:23]

Dry run: 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, 2017-07-05 14:24:20]

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

[commit-bot: I haz the power, 2017-07-05 14:24:21]

Dry run: This issue passed the CQ dry run.

[bcwhite, 2017-07-05 15:01:29]

bcwhite@chromium.org changed reviewers:
+ asvitkine@chromium.org

[Alexei Svitkine (slow), 2017-07-05 15:18:26]

lgtm

[bcwhite, 2017-07-05 15:23:29]

The CQ bit was checked by bcwhite@chromium.org

[commit-bot: I haz the power, 2017-07-05 15:23:39]

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, 2017-07-05 15:28:59]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1499268209263160, "parent_rev":
"a350dbdbfe91f9f2be20b8946d4352194e839d9e", "commit_rev":
"b4d87bb384bfc8b43cadc24160c0da01ab09f555"}

[commit-bot: I haz the power, 2017-07-05 15:29:13]

Description was changed from

==========
Remove typically unused local_metadata_ field.

The vast majority of histograms and their samples are now "persistent"
with the memory coming from a special memory segment. It's wasteful to
have a "local metadata" structure in each sample object that is never
used.

Instead, allocate the structure from the heap for only those objects
that need it and release it when those objects get destructed.

BUG=733380
==========

to

==========
Remove typically unused local_metadata_ field.

The vast majority of histograms and their samples are now "persistent"
with the memory coming from a special memory segment. It's wasteful to
have a "local metadata" structure in each sample object that is never
used.

Instead, allocate the structure from the heap for only those objects
that need it and release it when those objects get destructed.

BUG=733380

Review-Url: https://codereview.chromium.org/2973603002
Cr-Commit-Position: refs/heads/master@{#484282}
Committed:
https://chromium.googlesource.com/chromium/src/+/b4d87bb384bfc8b43cadc24160c0...
==========

[commit-bot: I haz the power, 2017-07-05 15:29:14]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/b4d87bb384bfc8b43cadc24160c0...