Remove unused TextTrack virtual functions

Remove unused TextTrack virtual functions

isClosedCaptions(), containsOnlyForcedSubtitles(),
isMainProgramContent() and isEasyToRead() are unused.

WebInbandTextTrack::isClosedCaptions() is implemented in
Chromium (WebInbandTextTrackImpl) by switching on kind. Since it
doesn't use OVERRIDE, it will still compile and can be removed
after a Blink roll.

BUG=315257
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=161398

[adamk, 2013-11-05 21:51:22]

lgtm

[commit-bot: I haz the power, 2013-11-05 22:16:24]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/philipj@opera.com/59913005/1

[commit-bot: I haz the power, 2013-11-05 22:35:12]

Retried try job too often on blink_presubmit for step(s) presubmit
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=blink_pres...

[philipj_slow, 2013-11-05 22:37:01]

Looks like I need an LGTM on public/web/WebInbandTextTrack.h as well.

[abarth-chromium, 2013-11-05 22:39:14]

public <--- LGTM

[commit-bot: I haz the power, 2013-11-05 22:39:52]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/philipj@opera.com/59913005/1

[commit-bot: I haz the power, 2013-11-06 00:03:40]

Change committed as 161398