Delete unused class/template ScopedMessageData.

Delete unused class/template ScopedMessageData.

This appears unused since cl https://codereview.webrtc.org/2564333002

BUG=webrtc:6424
Review-Url: https://codereview.webrtc.org/2652663002
Cr-Commit-Position: refs/heads/master@{#16229}
Committed: https://chromium.googlesource.com/external/webrtc/+/d83fb921a855531bfa58f873e2c668bfa735ad09

[nisse-webrtc, 2017-01-23 13:42:07]

nisse@webrtc.org changed reviewers:
+ deadbeef@webrtc.org, pthatcher@webrtc.org

[nisse-webrtc, 2017-01-23 13:42:08]

PTAL. This class appears unused, do you expect it to find any new uses?

I don't know the history and usage of the MessageQueue abstraction. It appears
the DelayedMessage class, defined in the same header, is also unused, should
that be deleted too?

[Taylor Brandstetter, 2017-01-23 18:26:57]

lgtm; I think these things can both be deleted. With abstractions like
"AsyncInvoker" and "rtc::Bind", there's less code that deals with Messages
directly.

[pthatcher1, 2017-01-23 21:35:46]

lgtm

[nisse-webrtc, 2017-01-24 07:51:04]

The CQ bit was checked by nisse@webrtc.org

[commit-bot: I haz the power, 2017-01-24 07:51:13]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.webrtc.org/...

[commit-bot: I haz the power, 2017-01-24 08:36:39]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1485244264321810, "parent_rev":
"c23b0b26df0ed7d482729dbdc47137ed7a7db788", "commit_rev":
"d83fb921a855531bfa58f873e2c668bfa735ad09"}

[commit-bot: I haz the power, 2017-01-24 08:36:41]

Description was changed from

==========
Delete unused class/template ScopedMessageData.

This appears unused since cl https://codereview.webrtc.org/2564333002

BUG=webrtc:6424
==========

to

==========
Delete unused class/template ScopedMessageData.

This appears unused since cl https://codereview.webrtc.org/2564333002

BUG=webrtc:6424

Review-Url: https://codereview.webrtc.org/2652663002
Cr-Commit-Position: refs/heads/master@{#16229}
Committed:
https://chromium.googlesource.com/external/webrtc/+/d83fb921a855531bfa58f873e...
==========

[commit-bot: I haz the power, 2017-01-24 08:36:42]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/external/webrtc/+/d83fb921a855531bfa58f873e...

[aleloi, 2017-01-24 09:20:24]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.webrtc.org/2654753003/ by aleloi@webrtc.org.

The reason for reverting is: ScopedMessageData can't be removed just yet. It
broke an internal project..