Don't allow form-feed (U+000C) as a WebVTT signature separator

Don't allow form-feed (U+000C) as a WebVTT signature separator

Per the WebVTT parser algorithm [1], only space, tab or newline (after
normalization) are allowed to follow the "WEBVTT" signature.

[1] https://w3c.github.io/webvtt/#webvtt-parser-algorithm

BUG=651777
Committed: https://crrev.com/84007ecf0f27d2074c70955d43cc1743ee39980a
Cr-Commit-Position: refs/heads/master@{#422093}

[fs, 2016-09-30 10:59:17]

The CQ bit was checked by fs@opera.com to run a CQ dry run

[commit-bot: I haz the power, 2016-09-30 10:59:30]

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

[fs, 2016-09-30 11:01:35]

The CQ bit was checked by fs@opera.com to run a CQ dry run

[commit-bot: I haz the power, 2016-09-30 11:01:41]

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

[fs, 2016-09-30 11:59:11]

fs@opera.com changed reviewers:
+ foolip@chromium.org

[commit-bot: I haz the power, 2016-09-30 12:01:40]

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

[commit-bot: I haz the power, 2016-09-30 12:01:41]

Dry run: This issue passed the CQ dry run.

[foolip, 2016-09-30 13:08:27]

The CQ bit was checked by foolip@chromium.org

[foolip, 2016-09-30 13:08:28]

lgtm

[commit-bot: I haz the power, 2016-09-30 13:08:39]

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, 2016-09-30 13:13:20]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-09-30 13:15:20]

Description was changed from

==========
Don't allow form-feed (U+000C) as a WebVTT signature separator

Per the WebVTT parser algorithm [1], only space, tab or newline (after
normalization) are allowed to follow the "WEBVTT" signature.

[1] https://w3c.github.io/webvtt/#webvtt-parser-algorithm

BUG=651777
==========

to

==========
Don't allow form-feed (U+000C) as a WebVTT signature separator

Per the WebVTT parser algorithm [1], only space, tab or newline (after
normalization) are allowed to follow the "WEBVTT" signature.

[1] https://w3c.github.io/webvtt/#webvtt-parser-algorithm

BUG=651777

Committed: https://crrev.com/84007ecf0f27d2074c70955d43cc1743ee39980a
Cr-Commit-Position: refs/heads/master@{#422093}
==========

[commit-bot: I haz the power, 2016-09-30 13:15:21]

Patchset 2 (id:??) landed as
https://crrev.com/84007ecf0f27d2074c70955d43cc1743ee39980a
Cr-Commit-Position: refs/heads/master@{#422093}