Do the codec string parsing for MSE in media, instead of Blink

Do the codec string parsing for MSE in media, instead of Blink

Other code paths parse the codecs string in media/ code
using media::ParseCodecString (see
KeySystemConfigSelector::IsSupportedContentType and
RendererBlinkPlatformImpl::MimeRegistry::supportsMediaMIMEType).
I created a new overload of WebSourceBufferImpl::addSourceBuffer that
does the same (https://codereview.chromium.org/1281663003/), now we can
remove blink::ContentType::codecs to consolidate all code paths.

BUG=none

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=200489

[wolenetz, 2015-08-12 17:33:00]

wolenetz@chromium.org changed reviewers:
+ wolenetz@chromium.org

[wolenetz, 2015-08-12 17:33:01]

FWIW, this looks to me like a good simplification/deduplication (removing
ContentType::codecs() string splitting in favor of already existing parsing in
Chromium media::ParseCodecString, pending the landing of the prereq Chromium CL,
of course.)

[servolk, 2015-08-12 21:30:42]

servolk@chromium.org changed reviewers:
+ philipj@opera.com

[servolk, 2015-08-12 21:32:16]

servolk@chromium.org changed reviewers:
+ abarth@chromium.org

[philipj_slow, 2015-08-13 08:19:32]

lgtm

It looks like the other entry point to the shared code path is
RendererBlinkPlatformImpl::MimeRegistry::supportsMediaSourceMIMEType, can you
say something to that effect in the description?

[philipj_slow, 2015-08-13 08:19:58]

Also, despite the path, this is Blink, not WebKit :)

[ddorwin, 2015-08-13 16:59:46]

ddorwin@chromium.org changed reviewers:
+ ddorwin@chromium.org

[ddorwin, 2015-08-13 16:59:47]

Please specifically mention "MSE" in the first line of the commit message. Also,
s/WebKit/Blink/.

[servolk, 2015-08-13 17:26:56]

On 2015/08/13 08:19:32, philipj wrote:
> lgtm
> 
> It looks like the other entry point to the shared code path is
> RendererBlinkPlatformImpl::MimeRegistry::supportsMediaSourceMIMEType, can you
> say something to that effect in the description?

done

[servolk, 2015-08-13 17:27:05]

On 2015/08/13 16:59:47, ddorwin wrote:
> Please specifically mention "MSE" in the first line of the commit message.
Also,
> s/WebKit/Blink/.

done

[wolenetz, 2015-08-13 17:55:21]

rs lgtm

[servolk, 2015-08-13 18:44:18]

The CQ bit was checked by servolk@chromium.org

[commit-bot: I haz the power, 2015-08-13 18:44:31]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1283573002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1283573002/1

[commit-bot: I haz the power, 2015-08-13 20:29:33]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=200489