Improve singleton example by assuming implementation is outside base/

Improve singleton example by assuming implementation is outside base/

The error messages returned by the compiler are hard to understand and
most singleton implementations live outside base/.

Also adds an example for leaky singletons because it's not clear that
DefaultSingletonTraits must still be friended.

Review-Url: https://codereview.chromium.org/2741493002
Cr-Commit-Position: refs/heads/master@{#455931}
Committed: https://chromium.googlesource.com/chromium/src/+/961c9d662de83d9d27547c48576e9df6ccfb5146

[Patrick Monette, 2017-03-08 19:39:07]

pmonette@chromium.org changed reviewers:
+ danakj@chromium.org

[Patrick Monette, 2017-03-08 19:39:08]

PTAL.

[Patrick Monette, 2017-03-08 19:41:31]

Description was changed from

==========
Improve singleton example by assuming implementation is outside base/

The error messages returned by the compiler are hard to understand and
most singleton implementations live outside base/.
==========

to

==========
Improve singleton example by assuming implementation is outside base/

The error messages returned by the compiler are hard to understand and
most singleton implementations live outside base/.

Also adds an example for leaky singletons because it's not clear that
DefaultSingletonTraits must still be friended.
==========

[danakj, 2017-03-09 21:18:22]

LGTM

https://codereview.chromium.org/2741493002/diff/1/base/memory/singleton.h
File base/memory/singleton.h (right):

https://codereview.chromium.org/2741493002/diff/1/base/memory/singleton.h#new...
base/memory/singleton.h:157: //   template <typename T>
nit: keep this as one line

[Patrick Monette, 2017-03-09 23:02:13]

https://codereview.chromium.org/2741493002/diff/1/base/memory/singleton.h
File base/memory/singleton.h (right):

https://codereview.chromium.org/2741493002/diff/1/base/memory/singleton.h#new...
base/memory/singleton.h:157: //   template <typename T>
On 2017/03/09 21:18:22, danakj wrote:
> nit: keep this as one line

That's how "git cl format" does it. IMO this example should show how
it will look after the formatting.

[danakj, 2017-03-09 23:04:18]

https://codereview.chromium.org/2741493002/diff/1/base/memory/singleton.h
File base/memory/singleton.h (right):

https://codereview.chromium.org/2741493002/diff/1/base/memory/singleton.h#new...
base/memory/singleton.h:157: //   template <typename T>
On 2017/03/09 23:02:13, Patrick Monette wrote:
> On 2017/03/09 21:18:22, danakj wrote:
> > nit: keep this as one line
> 
> That's how "git cl format" does it. IMO this example should show how
> it will look after the formatting.

Ah, fair enough.

[Patrick Monette, 2017-03-09 23:40:53]

Thanks!

[Patrick Monette, 2017-03-09 23:40:57]

The CQ bit was checked by pmonette@chromium.org

[commit-bot: I haz the power, 2017-03-09 23:41:42]

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, 2017-03-10 00:50:58]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1489102857617410, "parent_rev":
"0299edae682a3dd0c5f4ffd3fddde60b124695db", "commit_rev":
"961c9d662de83d9d27547c48576e9df6ccfb5146"}

[commit-bot: I haz the power, 2017-03-10 00:52:26]

Description was changed from

==========
Improve singleton example by assuming implementation is outside base/

The error messages returned by the compiler are hard to understand and
most singleton implementations live outside base/.

Also adds an example for leaky singletons because it's not clear that
DefaultSingletonTraits must still be friended.
==========

to

==========
Improve singleton example by assuming implementation is outside base/

The error messages returned by the compiler are hard to understand and
most singleton implementations live outside base/.

Also adds an example for leaky singletons because it's not clear that
DefaultSingletonTraits must still be friended.

Review-Url: https://codereview.chromium.org/2741493002
Cr-Commit-Position: refs/heads/master@{#455931}
Committed:
https://chromium.googlesource.com/chromium/src/+/961c9d662de83d9d27547c48576e...
==========

[commit-bot: I haz the power, 2017-03-10 00:52:27]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/961c9d662de83d9d27547c48576e...