Remove pure-virtual interface UndoStep

Remove pure-virtual interface UndoStep

This patch removes the pure-virtual interface |UndoStep|, and let its
only implementation |EditCommandComposition| take its place.

Follow up patches will clean up names of classes and functions.

BUG=682129
Review-Url: https://codereview.chromium.org/2642653002
Cr-Commit-Position: refs/heads/master@{#444315}
Committed: https://chromium.googlesource.com/chromium/src/+/1d898450465e5348f291e38efc2e80684b5134b5

[Xiaocheng, 2017-01-18 07:54:12]

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

[commit-bot: I haz the power, 2017-01-18 07:54:36]

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

[Xiaocheng, 2017-01-18 08:14:55]

xiaochengh@chromium.org changed reviewers:
+ yosin@chromium.org

[Xiaocheng, 2017-01-18 08:14:55]

PTAL.

[yosin_UTC9, 2017-01-18 08:55:14]

lgtm

this is a small step for a use but a great leap for editing team!

[Xiaocheng, 2017-01-18 09:01:11]

The CQ bit was unchecked by xiaochengh@chromium.org

[Xiaocheng, 2017-01-18 09:01:13]

The CQ bit was checked by xiaochengh@chromium.org

[commit-bot: I haz the power, 2017-01-18 09:01:49]

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, 2017-01-18 09:38:08]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1484730073425920, "parent_rev":
"28efa3f1874a4f8cee744f7a1f00e6127b0b600b", "commit_rev":
"1d898450465e5348f291e38efc2e80684b5134b5"}

[commit-bot: I haz the power, 2017-01-18 09:38:42]

Description was changed from

==========
Remove pure-virtual interface UndoStep

This patch removes the pure-virtual interface |UndoStep|, and let its
only implementation |EditCommandComposition| take its place.

Follow up patches will clean up names of classes and functions.

BUG=682129
==========

to

==========
Remove pure-virtual interface UndoStep

This patch removes the pure-virtual interface |UndoStep|, and let its
only implementation |EditCommandComposition| take its place.

Follow up patches will clean up names of classes and functions.

BUG=682129

Review-Url: https://codereview.chromium.org/2642653002
Cr-Commit-Position: refs/heads/master@{#444315}
Committed:
https://chromium.googlesource.com/chromium/src/+/1d898450465e5348f291e38efc2e...
==========

[commit-bot: I haz the power, 2017-01-18 09:38:42]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/1d898450465e5348f291e38efc2e...