Delete dead code for CurrentlyOpenTabs

Delete dead code for CurrentlyOpenTabs

RecentTabsManager#getCurrentlyOpenTabs() always returns null,
and from that point on all this other code seems to be unused.

BUG=659631
Committed: https://crrev.com/04b297ee5b0a8061c42fd23ffe04148b3d27ce76
Cr-Commit-Position: refs/heads/master@{#441387}

[Michael van Ouwerkerk, 2016-12-23 11:49:25]

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

[commit-bot: I haz the power, 2016-12-23 11:49:30]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[Michael van Ouwerkerk, 2016-12-23 11:51:29]

Description was changed from

==========
Delete dead code for CurrentlyOpenTabs

BUG=659631
==========

to

==========
Delete dead code for CurrentlyOpenTabs

RecentTabsManager#getCurrentlyOpenTabs() always returns null,
and from that point on all this other code seems to be unused.

BUG=659631
==========

[Michael van Ouwerkerk, 2016-12-23 11:53:08]

mvanouwerkerk@chromium.org changed reviewers:
+ bauerb@chromium.org, tedchoc@chromium.org

[Michael van Ouwerkerk, 2016-12-23 11:53:08]

Bernhard, Ted, could you take a look please? It seems maybe in the past there
was an intention to override or complete this code. As it stands, it is dead
code and is not under active development.

[commit-bot: I haz the power, 2016-12-23 12:54:56]

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

[commit-bot: I haz the power, 2016-12-23 12:54:57]

Dry run: This issue passed the CQ dry run.

[Ted C, 2016-12-27 17:32:48]

lgtm ... do we need to do any cleanup when we delete a preference?

If someone were to have had this set (I believe it was in the document mode
days) and we have the unfortunate misfortune to add the same preference name
back but with a different non-boolean type, will Chrome freak out?  bauerb@ will
likely know that answer more than me, but I would look at previous removals of
native prefs to see if they do anything special to clean up

[Bernhard Bauer, 2017-01-03 10:15:51]

On 2016/12/27 17:32:48, Ted C wrote:
> lgtm ... do we need to do any cleanup when we delete a preference?
> 
> If someone were to have had this set (I believe it was in the document mode
> days) and we have the unfortunate misfortune to add the same preference name
> back but with a different non-boolean type, will Chrome freak out?  bauerb@
will
> likely know that answer more than me, but I would look at previous removals of
> native prefs to see if they do anything special to clean up

We sometimes clean up deprecated preferences (by renaming them to something like
...Deprecated and only accessing them to clear them, with a comment to remove
the code in X milestones, which we then promptly proceed to forget about 😉).

Is this preference synced? If it is, we need to be careful not to delete it in a
new version, which would then cause the deletion to be synced back to an older
version.

We generally deal gracefully with type conflicts by just ignoring values of an
unexpected type (although a Debug build might still crash), but again, if the
preference is synced, we would end up with a value that's unusable in either the
old or the new version.

So, TL;DR: if the preference is synced, it's probably best to leave it
registered forever to prevent sync conflicts, otherwise we can add migration
code to remove it (but it probably wouldn't be the end of the world if we
didn't).

[Michael van Ouwerkerk, 2017-01-03 15:05:24]

The kNtpCollapsedCurrentlyOpenTabs pref is not synced. This seems like an
obscure one, are you ok with just deleting it right away, without deprecation
and cleanup?

[Michael van Ouwerkerk, 2017-01-04 12:28:22]

Pinging Mr Bauer... is this fine with you?

[Bernhard Bauer, 2017-01-04 15:20:28]

lgtm

[Michael van Ouwerkerk, 2017-01-04 15:20:46]

The CQ bit was checked by mvanouwerkerk@chromium.org

[commit-bot: I haz the power, 2017-01-04 15:21:02]

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, 2017-01-04 16:26:49]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1483543246971400, "parent_rev":
"6d4257f5644800cf7d55d259c9dff537de52302d", "commit_rev":
"13ff0241f0bbce821ccc085390f4cfef0c88eef3"}

[commit-bot: I haz the power, 2017-01-04 16:27:18]

Description was changed from

==========
Delete dead code for CurrentlyOpenTabs

RecentTabsManager#getCurrentlyOpenTabs() always returns null,
and from that point on all this other code seems to be unused.

BUG=659631
==========

to

==========
Delete dead code for CurrentlyOpenTabs

RecentTabsManager#getCurrentlyOpenTabs() always returns null,
and from that point on all this other code seems to be unused.

BUG=659631

Review-Url: https://codereview.chromium.org/2604453004
==========

[commit-bot: I haz the power, 2017-01-04 16:27:20]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2017-01-04 16:29:12]

Description was changed from

==========
Delete dead code for CurrentlyOpenTabs

RecentTabsManager#getCurrentlyOpenTabs() always returns null,
and from that point on all this other code seems to be unused.

BUG=659631

Review-Url: https://codereview.chromium.org/2604453004
==========

to

==========
Delete dead code for CurrentlyOpenTabs

RecentTabsManager#getCurrentlyOpenTabs() always returns null,
and from that point on all this other code seems to be unused.

BUG=659631

Committed: https://crrev.com/04b297ee5b0a8061c42fd23ffe04148b3d27ce76
Cr-Commit-Position: refs/heads/master@{#441387}
==========

[commit-bot: I haz the power, 2017-01-04 16:29:13]

Patchset 1 (id:??) landed as
https://crrev.com/04b297ee5b0a8061c42fd23ffe04148b3d27ce76
Cr-Commit-Position: refs/heads/master@{#441387}