Revert of Map WebURLRequest::RequestContextPlugin to RESOURCE_TYPE_OBJECT.

Revert of Map WebURLRequest::RequestContextPlugin to RESOURCE_TYPE_OBJECT. (patchset #6 id:600001 of https://codereview.chromium.org/630973002/)

Reason for revert:
Speculative revert since it might cause browser test PDFExtensionTest.BasicPlugin to fail.

http://build.chromium.org/p/chromium.webkit/builders/Linux%20Tests%20(dbg)/builds/4962
http://build.chromium.org/p/chromium.webkit/builders/Mac10.8%20Tests/builds/11223
http://build.chromium.org/p/chromium.webkit/builders/Win7%20Tests/builds/7530

Original issue's description:
> Map WebURLRequest::RequestContextPlugin to RESOURCE_TYPE_OBJECT.
>
> The WebRequest API should treat both object requests, and requests made
> from those objects (e.g. Flash requesting an .mp4 resource) as type
> Object. We used to do this, then I broke it. :( Now I'm fixing it. :)
>
> BUG=410382
> R=vabr@chromium.org
>
> Committed: https://crrev.com/c3e50e6354188999da307094c5c037d5933f1bc3
> Cr-Commit-Position: refs/heads/master@{#308787}

TBR=jochen@chromium.org,jam@chromium.org,vabr@chromium.org,mkwst@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=410382
Committed: https://crrev.com/9ae580a9293de35ec2e97b303967c809192c646c
Cr-Commit-Position: refs/heads/master@{#308834}

[jianli, 2014-12-17 19:15:09]

Created Revert of Map WebURLRequest::RequestContextPlugin to
RESOURCE_TYPE_OBJECT.

[commit-bot: I haz the power, 2014-12-17 19:15:53]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/809103003/1

[commit-bot: I haz the power, 2014-12-17 19:16:52]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-12-17 19:17:34]

Patchset 1 (id:??) landed as
https://crrev.com/9ae580a9293de35ec2e97b303967c809192c646c
Cr-Commit-Position: refs/heads/master@{#308834}

[jianli, 2014-12-17 21:17:44]

The revert fixed the issue.

[Mike West, 2014-12-17 21:18:27]

On 2014/12/17 21:17:44, jianli wrote:
> The revert fixed the issue.

LGTM, then. Thanks.