android: JavaRef type behaviour improvements.

android: JavaRef type behaviour improvements.

Several improvements to the behaviour of JavaRef types:

1) Make JavaRef's default constructor public. You can get a null JavaRef
   by conversion from nullptr_t already, so default-constructing one
   seems fine too.
2) Replace templating on a second generic type U with simply JavaRef<T>.
   All existing usage works fine with this; it simplifies the
   implementation and creates fewer ambiguities.
3) Add comments to ScopedJavaLocalRef about the behaviour of the
   constructor and Reset() overloads that take (JNIEnv*, T) as
   parameters, as the current behaviour is confusing but can't yet be
   changed.

BUG=519562
Committed: https://crrev.com/7588d910ee25079d1d5687cd3b6c9a39738d84c1
Cr-Commit-Position: refs/heads/master@{#435210}

[Torne, 2016-11-28 17:15:25]

torne@chromium.org changed reviewers:
+ rmcilroy@chromium.org

[Torne, 2016-11-28 17:15:26]

Some misc cleanups I did while thinking about whether to add more combinations
of constructor here. I haven't actually added new ones because it's a bit
confusing with the existing ambiguous behaviour and I think it's best avoided
for now until the existing usage has been cleaned up somewhat, but these
cleanups are probably worth landing on their own.

[rmcilroy, 2016-11-29 12:16:26]

lgtm

[Torne, 2016-11-29 12:31:56]

The CQ bit was checked by torne@chromium.org

[commit-bot: I haz the power, 2016-11-29 12:32:06]

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, 2016-11-29 13:56:14]

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

[commit-bot: I haz the power, 2016-11-29 13:56:15]

Try jobs failed on following builders:
  linux_android_rel_ng on master.tryserver.chromium.android (JOB_FAILED,
https://build.chromium.org/p/tryserver.chromium.android/builders/linux_androi...)

[Torne, 2016-11-30 10:10:50]

The CQ bit was checked by torne@chromium.org

[commit-bot: I haz the power, 2016-11-30 10:11:07]

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, 2016-11-30 10:55:28]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1480500650550730, "parent_rev":
"ae23ffa4616b8857c70bdefd74ec7198c3e885b0", "commit_rev":
"8dfe8f1aeffbca8e3efebb0d6aa836958eb39303"}

[commit-bot: I haz the power, 2016-11-30 10:55:54]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-11-30 10:58:45]

Description was changed from

==========
android: JavaRef type behaviour improvements.

Several improvements to the behaviour of JavaRef types:

1) Make JavaRef's default constructor public. You can get a null JavaRef
   by conversion from nullptr_t already, so default-constructing one
   seems fine too.
2) Replace templating on a second generic type U with simply JavaRef<T>.
   All existing usage works fine with this; it simplifies the
   implementation and creates fewer ambiguities.
3) Add comments to ScopedJavaLocalRef about the behaviour of the
   constructor and Reset() overloads that take (JNIEnv*, T) as
   parameters, as the current behaviour is confusing but can't yet be
   changed.

BUG=519562
==========

to

==========
android: JavaRef type behaviour improvements.

Several improvements to the behaviour of JavaRef types:

1) Make JavaRef's default constructor public. You can get a null JavaRef
   by conversion from nullptr_t already, so default-constructing one
   seems fine too.
2) Replace templating on a second generic type U with simply JavaRef<T>.
   All existing usage works fine with this; it simplifies the
   implementation and creates fewer ambiguities.
3) Add comments to ScopedJavaLocalRef about the behaviour of the
   constructor and Reset() overloads that take (JNIEnv*, T) as
   parameters, as the current behaviour is confusing but can't yet be
   changed.

BUG=519562

Committed: https://crrev.com/7588d910ee25079d1d5687cd3b6c9a39738d84c1
Cr-Commit-Position: refs/heads/master@{#435210}
==========

[commit-bot: I haz the power, 2016-11-30 10:58:47]

Patchset 1 (id:??) landed as
https://crrev.com/7588d910ee25079d1d5687cd3b6c9a39738d84c1
Cr-Commit-Position: refs/heads/master@{#435210}