Alias |ranges| so it appears in minidump.

Alias |ranges| so it appears in minidump.

BUG=586622
Review-Url: https://codereview.chromium.org/2970873002
Cr-Commit-Position: refs/heads/master@{#484159}
Committed: https://chromium.googlesource.com/chromium/src/+/4485eb651f6f09c3183285927fe82d17fcd7a13e

[bcwhite, 2017-07-04 19:09:16]

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

[commit-bot: I haz the power, 2017-07-04 19:09:27]

Dry run: CQ is trying da patch.

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

[bcwhite, 2017-07-04 19:10:20]

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

[Alexei Svitkine (slow), 2017-07-04 19:33:41]

lgtm

[bcwhite, 2017-07-04 19:39:18]

The CQ bit was unchecked by bcwhite@chromium.org

[bcwhite, 2017-07-04 19:39:22]

The CQ bit was checked by bcwhite@chromium.org

[commit-bot: I haz the power, 2017-07-04 19:39:36]

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, 2017-07-04 21:39:09]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1499197162434000, "parent_rev":
"4e72a1554a6b4efb3ea711ead4876f0f3e276e45", "commit_rev":
"4485eb651f6f09c3183285927fe82d17fcd7a13e"}

[commit-bot: I haz the power, 2017-07-04 21:39:23]

Description was changed from

==========
Alias |ranges| so it appears in minidump.

BUG=586622
==========

to

==========
Alias |ranges| so it appears in minidump.

BUG=586622

Review-Url: https://codereview.chromium.org/2970873002
Cr-Commit-Position: refs/heads/master@{#484159}
Committed:
https://chromium.googlesource.com/chromium/src/+/4485eb651f6f09c3183285927fe8...
==========

[commit-bot: I haz the power, 2017-07-04 21:39:25]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/4485eb651f6f09c3183285927fe8...

[brucedawson, 2017-08-17 19:28:00]

brucedawson@chromium.org changed reviewers:
+ brucedawson@chromium.org

[brucedawson, 2017-08-17 19:28:01]

https://codereview.chromium.org/2970873002/diff/1/base/metrics/histogram.cc
File base/metrics/histogram.cc (right):

https://codereview.chromium.org/2970873002/diff/1/base/metrics/histogram.cc#n...
base/metrics/histogram.cc:121: base::debug::Alias(&ranges);  // TODO(bcwhite):
Remove after crbug/586622.
Be aware that this technique doesn't work very well. Because ranges is a pointer
all that this ensures is that the compiler won't discard the pointer before the
end of the function, which was already guaranteed by the return statement. The
Alias() function does nothing to ensure that the memory pointed to be ranges is
retained in crash dumps. And, either way, the effect of Alias() only extends to
the end of the function where it is called.

See https://chromium-review.googlesource.com/c/619112

[bcwhite, 2017-08-18 05:09:01]

https://codereview.chromium.org/2970873002/diff/1/base/metrics/histogram.cc
File base/metrics/histogram.cc (right):

https://codereview.chromium.org/2970873002/diff/1/base/metrics/histogram.cc#n...
base/metrics/histogram.cc:121: base::debug::Alias(&ranges);  // TODO(bcwhite):
Remove after crbug/586622.
On 2017/08/17 19:28:00, brucedawson wrote:
> Be aware that this technique doesn't work very well. Because ranges is a
pointer
> all that this ensures is that the compiler won't discard the pointer before
the
> end of the function, which was already guaranteed by the return statement. The
> Alias() function does nothing to ensure that the memory pointed to be ranges
is
> retained in crash dumps. And, either way, the effect of Alias() only extends
to
> the end of the function where it is called.
> 
> See https://chromium-review.googlesource.com/c/619112

Yeah...  I've noticed that.  :-(  It would be nice if it somehow gave a hint to
Crashpad and got that memory included in a dump.