Make FlexfecReceiver a concrete class.

Make FlexfecReceiver a concrete class.

There is no need for it to be an interface.

In this CL, I also took the opportunity to make two small fixes:
- remove the 'flexfec_' prefix from some member variables
- remove unnecessary use of a stringstream object

BUG=webrtc:5654
Committed: https://crrev.com/0a4c1616bf40a3c33aac46e50c6f9ac79a15ca1b
Cr-Commit-Position: refs/heads/master@{#14919}

[brandtr, 2016-11-02 16:07:31]

brandtr@webrtc.org changed reviewers:
+ stefan@webrtc.org

[brandtr, 2016-11-02 16:07:31]

Remove interface from FlexfecReceiver as well.

[stefan-webrtc, 2016-11-03 13:38:14]

lgtm

[brandtr, 2016-11-03 14:38:03]

The CQ bit was checked by brandtr@webrtc.org

[brandtr, 2016-11-03 14:38:04]

The patchset sent to the CQ was uploaded after l-g-t-m from stefan@webrtc.org
Link to the patchset: https://codereview.webrtc.org/2471073003/#ps20001 (title:
"Update fuzzer.")

[commit-bot: I haz the power, 2016-11-03 14:38:12]

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, 2016-11-03 15:18:30]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-11-03 15:40:56]

Description was changed from

==========
Make FlexfecReceiver a concrete class.

There is no need for it to be an interface.

In this CL, I also took the opportunity to make two small fixes:
- remove the 'flexfec_' prefix from some member variables
- remove unnecessary use of a stringstream object

BUG=webrtc:5654
==========

to

==========
Make FlexfecReceiver a concrete class.

There is no need for it to be an interface.

In this CL, I also took the opportunity to make two small fixes:
- remove the 'flexfec_' prefix from some member variables
- remove unnecessary use of a stringstream object

BUG=webrtc:5654

Committed: https://crrev.com/0a4c1616bf40a3c33aac46e50c6f9ac79a15ca1b
Cr-Commit-Position: refs/heads/master@{#14919}
==========

[commit-bot: I haz the power, 2016-11-03 15:40:57]

Patchset 2 (id:??) landed as
https://crrev.com/0a4c1616bf40a3c33aac46e50c6f9ac79a15ca1b
Cr-Commit-Position: refs/heads/master@{#14919}