Implement NullVideoDecoder to avoid crash on unsupported decoders.

Implement NullVideoDecoder to avoid crash on unsupported decoders.

There is a use case with external codec factories that only support
encoding but not decoding for a given type. This leads to a crash
due to null being registered as codec (after a DCHECK).

This CL adds a NullVideoDecoder that is used instead of the null to
not crash but log to LS_ERROR.

BUG=webrtc:5249
Committed: https://crrev.com/e03ac51aa16f9aa9902493d61fedacbe05734eba
Cr-Commit-Position: refs/heads/master@{#11475}

[joachim, 2016-02-01 22:37:15]

jbauch@webrtc.org changed reviewers:
+ pbos@webrtc.org

[joachim, 2016-02-01 22:37:16]

Ptal, do you have some suggestions how I could write tests for that?

[pbos-webrtc, 2016-02-02 13:50:32]

pbos@webrtc.org changed reviewers:
+ noahric@chromium.org

[pbos-webrtc, 2016-02-02 13:50:33]

+R noahric@, since you guys needed this, can you take a look and see if this
looks like it works for you? I can review after that.

[pbos-webrtc, 2016-02-02 13:59:14]

https://codereview.webrtc.org/1657023002/diff/20001/webrtc/video/video_decode...
File webrtc/video/video_decoder.cc (right):

https://codereview.webrtc.org/1657023002/diff/20001/webrtc/video/video_decode...
webrtc/video/video_decoder.cc:30: return new NullVideoDecoder();
I'd prefer a log here as well.

[noahric, 2016-02-02 14:06:44]

Cool, LGTM.

https://codereview.webrtc.org/1657023002/diff/20001/webrtc/video/video_decode...
File webrtc/video/video_decoder.cc (right):

https://codereview.webrtc.org/1657023002/diff/20001/webrtc/video/video_decode...
webrtc/video/video_decoder.cc:181: return "null";
Maybe NullVideoDecoder, so the logging doesn't look weird ("why is this logging
null? is it actually null?").

[pbos-webrtc, 2016-02-02 14:11:15]

lgtm with Noah's comment fixed.

[joachim, 2016-02-02 14:31:33]

All done, thanks

https://codereview.webrtc.org/1657023002/diff/20001/webrtc/video/video_decode...
File webrtc/video/video_decoder.cc (right):

https://codereview.webrtc.org/1657023002/diff/20001/webrtc/video/video_decode...
webrtc/video/video_decoder.cc:30: return new NullVideoDecoder();
On 2016/02/02 13:59:13, pbos-webrtc wrote:
> I'd prefer a log here as well.

Done.

https://codereview.webrtc.org/1657023002/diff/20001/webrtc/video/video_decode...
webrtc/video/video_decoder.cc:181: return "null";
On 2016/02/02 14:06:43, noahric wrote:
> Maybe NullVideoDecoder, so the logging doesn't look weird ("why is this
logging
> null? is it actually null?").

Done.

[pbos-webrtc, 2016-02-02 14:32:52]

lgtm

[joachim, 2016-02-02 14:34:21]

The CQ bit was checked by jbauch@webrtc.org

[joachim, 2016-02-02 14:34:22]

The patchset sent to the CQ was uploaded after l-g-t-m from noahric@chromium.org
Link to the patchset: https://codereview.webrtc.org/1657023002/#ps40001 (title:
"Feedback")

[commit-bot: I haz the power, 2016-02-02 14:36:33]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1657023002/40001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1657023002/40001

[joachim, 2016-02-02 14:56:09]

jbauch@webrtc.org changed reviewers:
+ mflodman@webrtc.org

[joachim, 2016-02-02 14:56:10]

@mflodman: ptal for owner review of webrtc/video_decoder.h

[commit-bot: I haz the power, 2016-02-02 15:07:06]

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

[commit-bot: I haz the power, 2016-02-02 15:07:07]

Try jobs failed on following builders:
  presubmit on tryserver.webrtc (JOB_FAILED,
http://build.chromium.org/p/tryserver.webrtc/builders/presubmit/builds/3192)

[joachim, 2016-02-03 13:10:05]

On 2016/02/02 14:56:10, joachim wrote:
> @mflodman: ptal for owner review of webrtc/video_decoder.h

mflodman, ping

[mflodman, 2016-02-03 13:35:23]

LGTM

[joachim, 2016-02-03 13:47:02]

The CQ bit was checked by jbauch@webrtc.org

[commit-bot: I haz the power, 2016-02-03 13:47:09]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1657023002/40001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1657023002/40001

[commit-bot: I haz the power, 2016-02-03 13:51:53]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2016-02-03 13:52:02]

Description was changed from

==========
Implement NullVideoDecoder to avoid crash on unsupported decoders.

There is a use case with external codec factories that only support
encoding but not decoding for a given type. This leads to a crash
due to null being registered as codec (after a DCHECK).

This CL adds a NullVideoDecoder that is used instead of the null to
not crash but log to LS_ERROR.

BUG=webrtc:5249
==========

to

==========
Implement NullVideoDecoder to avoid crash on unsupported decoders.

There is a use case with external codec factories that only support
encoding but not decoding for a given type. This leads to a crash
due to null being registered as codec (after a DCHECK).

This CL adds a NullVideoDecoder that is used instead of the null to
not crash but log to LS_ERROR.

BUG=webrtc:5249

Committed: https://crrev.com/e03ac51aa16f9aa9902493d61fedacbe05734eba
Cr-Commit-Position: refs/heads/master@{#11475}
==========

[commit-bot: I haz the power, 2016-02-03 13:52:03]

Patchset 3 (id:??) landed as
https://crrev.com/e03ac51aa16f9aa9902493d61fedacbe05734eba
Cr-Commit-Position: refs/heads/master@{#11475}