Fix scoped_refptr copy/move-conversion overload resolution

Fix scoped_refptr copy/move-conversion overload resolution

When an overloaded function takes a scoped_refptr<U> for a different U for
different overloads, the compiler doesn't know which one to take when passing a
scoped_refptr<D>, even if D* is only convertible to one of the U*.
Use SFINAE to eliminate copy/move-convert constructors that shouldn't take part
in the overload resolution.

BUG=None

Committed: https://crrev.com/5313092de707a68b9fc7cf930677fe127fc5317d
Cr-Commit-Position: refs/heads/master@{#388388}

[piman, 2016-04-19 23:11:09]

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

[piman, 2016-04-19 23:15:02]

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

[commit-bot: I haz the power, 2016-04-19 23:15:52]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1904603002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1904603002/20001

[danakj, 2016-04-19 23:19:46]

LGTM

https://codereview.chromium.org/1904603002/diff/20001/base/memory/ref_counted.h
File base/memory/ref_counted.h (right):

https://codereview.chromium.org/1904603002/diff/20001/base/memory/ref_counted...
base/memory/ref_counted.h:288: typename Dummy = typename std::enable_if<
nit: don't need to name it Dummy, just "typename = "

https://codereview.chromium.org/1904603002/diff/20001/base/memory/ref_counted...
base/memory/ref_counted.h:301: typename Dummy = typename std::enable_if<
ditto

[piman, 2016-04-19 23:22:32]

The CQ bit was checked by piman@chromium.org

[piman, 2016-04-19 23:22:32]

The patchset sent to the CQ was uploaded after l-g-t-m from danakj@chromium.org
Link to the patchset: https://codereview.chromium.org/1904603002/#ps40001
(title: "remove dummy type name")

[commit-bot: I haz the power, 2016-04-19 23:22:52]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1904603002/40001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1904603002/40001

[piman, 2016-04-19 23:24:49]

https://codereview.chromium.org/1904603002/diff/20001/base/memory/ref_counted.h
File base/memory/ref_counted.h (right):

https://codereview.chromium.org/1904603002/diff/20001/base/memory/ref_counted...
base/memory/ref_counted.h:288: typename Dummy = typename std::enable_if<
On 2016/04/19 23:19:46, danakj wrote:
> nit: don't need to name it Dummy, just "typename = "

Done.

https://codereview.chromium.org/1904603002/diff/20001/base/memory/ref_counted...
base/memory/ref_counted.h:301: typename Dummy = typename std::enable_if<
On 2016/04/19 23:19:46, danakj wrote:
> ditto

Done.

[commit-bot: I haz the power, 2016-04-20 01:04:50]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2016-04-22 19:19:20]

Description was changed from

==========
Fix scoped_refptr copy/move-conversion overload resolution

When an overloaded function takes a scoped_refptr<U> for a different U for
different overloads, the compiler doesn't know which one to take when passing a
scoped_refptr<D>, even if D* is only convertible to one of the U*.
Use SFINAE to eliminate copy/move-convert constructors that shouldn't take part
in the overload resolution.

BUG=None
==========

to

==========
Fix scoped_refptr copy/move-conversion overload resolution

When an overloaded function takes a scoped_refptr<U> for a different U for
different overloads, the compiler doesn't know which one to take when passing a
scoped_refptr<D>, even if D* is only convertible to one of the U*.
Use SFINAE to eliminate copy/move-convert constructors that shouldn't take part
in the overload resolution.

BUG=None

Committed: https://crrev.com/5313092de707a68b9fc7cf930677fe127fc5317d
Cr-Commit-Position: refs/heads/master@{#388388}
==========

[commit-bot: I haz the power, 2016-04-22 19:19:21]

Patchset 3 (id:??) landed as
https://crrev.com/5313092de707a68b9fc7cf930677fe127fc5317d
Cr-Commit-Position: refs/heads/master@{#388388}