Implement host settings migration.

Implement host settings migration.

This CL adds support for external messages, asynchronous handlers and a
getSettings message. It also tightens the default externally_connectable
to deny access to the new API to all origins, including other extensions,
for the time being.

Review-Url: https://codereview.chromium.org/2671103002
Cr-Commit-Position: refs/heads/master@{#448128}
Committed: https://chromium.googlesource.com/chromium/src/+/9760c9890b917e02136c6d32f89fd1a432c17d8a

[Jamie, 2017-02-03 22:43:09]

jamiewalch@chromium.org changed reviewers:
+ kelvinp@chromium.org

[Jamie, 2017-02-03 22:43:09]

PTAL

[kelvinp, 2017-02-03 22:54:57]

lgtm

[Jamie, 2017-02-03 23:16:24]

The CQ bit was checked by jamiewalch@chromium.org

[commit-bot: I haz the power, 2017-02-03 23:16:40]

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, 2017-02-04 00:48:57]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1486163784298520, "parent_rev":
"a67e9c930f58bb30971795c3da424dfe3bf00906", "commit_rev":
"9760c9890b917e02136c6d32f89fd1a432c17d8a"}

[commit-bot: I haz the power, 2017-02-04 00:49:29]

Description was changed from

==========
Implement host settings migration.

This CL adds support for external messages, asynchronous handlers and a
getSettings message. It also tightens the default externally_connectable
to deny access to the new API to all origins, including other extensions,
for the time being.
==========

to

==========
Implement host settings migration.

This CL adds support for external messages, asynchronous handlers and a
getSettings message. It also tightens the default externally_connectable
to deny access to the new API to all origins, including other extensions,
for the time being.

Review-Url: https://codereview.chromium.org/2671103002
Cr-Commit-Position: refs/heads/master@{#448128}
Committed:
https://chromium.googlesource.com/chromium/src/+/9760c9890b917e02136c6d32f89f...
==========

[commit-bot: I haz the power, 2017-02-04 00:49:30]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/9760c9890b917e02136c6d32f89f...