mojo: Make EqualsTraits<> part of public C++ API

mojo: Make EqualsTraits<> part of public C++ API

Users of mapped types sometimes need to provide their own custom
comparsion functions for classes that do not provide operator==() or an
Equals() method. Move EqualsTraits<> out of mojo internals, similar to
how CloneTraits<> is handled.

BUG=714689
TEST=compiles

Review-Url: https://codereview.chromium.org/2837353002
Cr-Commit-Position: refs/heads/master@{#467160}
Committed: https://chromium.googlesource.com/chromium/src/+/b9404e80f80b4bddfa2c24ca042393ceb5a5b882

[James Cook, 2017-04-25 18:15:45]

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

[James Cook, 2017-04-25 18:16:07]

jamescook@chromium.org changed reviewers:
+ yzshen@chromium.org

[James Cook, 2017-04-25 18:16:08]

yzshen, please take a look.

[commit-bot: I haz the power, 2017-04-25 18:16:21]

Dry run: CQ is trying da patch.

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

[yzshen1, 2017-04-25 18:22:57]

lgtm

[commit-bot: I haz the power, 2017-04-25 18:27:23]

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

[commit-bot: I haz the power, 2017-04-25 18:27:23]

Dry run: Try jobs failed on following builders:
  ios-simulator on master.tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/ios-simulator/bui...)

[James Cook, 2017-04-25 21:57:26]

The CQ bit was checked by jamescook@chromium.org

[James Cook, 2017-04-25 21:57:26]

The patchset sent to the CQ was uploaded after l-g-t-m from yzshen@chromium.org
Link to the patchset: https://codereview.chromium.org/2837353002/#ps20001
(title: "fix build")

[commit-bot: I haz the power, 2017-04-25 21:57:56]

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, 2017-04-25 23:24:24]

CQ is committing da patch.

Bot data: {"patchset_id": 20001, "attempt_start_ts": 1493157446469420,
"parent_rev": "43ec6dfaa0c7df6c01fc05649593808bbe5e051b", "commit_rev":
"b9404e80f80b4bddfa2c24ca042393ceb5a5b882"}

[commit-bot: I haz the power, 2017-04-25 23:24:34]

Description was changed from

==========
mojo: Make EqualsTraits<> part of public C++ API

Users of mapped types sometimes need to provide their own custom
comparsion functions for classes that do not provide operator==() or an
Equals() method. Move EqualsTraits<> out of mojo internals, similar to
how CloneTraits<> is handled.

BUG=714689
TEST=compiles
==========

to

==========
mojo: Make EqualsTraits<> part of public C++ API

Users of mapped types sometimes need to provide their own custom
comparsion functions for classes that do not provide operator==() or an
Equals() method. Move EqualsTraits<> out of mojo internals, similar to
how CloneTraits<> is handled.

BUG=714689
TEST=compiles

Review-Url: https://codereview.chromium.org/2837353002
Cr-Commit-Position: refs/heads/master@{#467160}
Committed:
https://chromium.googlesource.com/chromium/src/+/b9404e80f80b4bddfa2c24ca0423...
==========

[commit-bot: I haz the power, 2017-04-25 23:24:35]

Committed patchset #2 (id:20001) as
https://chromium.googlesource.com/chromium/src/+/b9404e80f80b4bddfa2c24ca0423...