Revert of Attach a SecurityStyle to each request in ResourceLoader

Revert of Attach a SecurityStyle to each request in ResourceLoader (patchset #9 id:160001 of https://codereview.chromium.org/1244863003/)

Reason for revert:
SecurityStyleChanged browser test is flaky after this change: http://build.chromium.org/p/chromium.linux/builders/Linux%20Tests

Original issue's description:
> Attach a SecurityStyle to each request in ResourceLoader
>
> This CL adds a SecurityStyle to the serialized security information that
> is sent with each request from the browser to the renderer. The
> SecurityStyle describes the individual resource, not any bigger-picture
> concerns like mixed content. The per-request SecurityStyle will be
> displayed in DevTools to help developers diagnose SSL issues on
> subresources.
>
> BUG=502118, 445234
>
> Committed: https://crrev.com/5318895a4dd623caf5d152461684935c6e874e12
> Cr-Commit-Position: refs/heads/master@{#340762}

TBR=creis@chromium.org,davidben@chromium.org,palmer@chromium.org,msw@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=502118, 445234
Committed: https://crrev.com/0c388aaf008fe3549e436fdfa3b2d2ee95b9a011
Cr-Commit-Position: refs/heads/master@{#340785}

[estark, 2015-07-28 22:39:07]

Created Revert of Attach a SecurityStyle to each request in ResourceLoader

[commit-bot: I haz the power, 2015-07-28 22:41:02]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1259253009/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1259253009/1

[commit-bot: I haz the power, 2015-07-28 22:42:56]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-07-28 22:43:29]

Patchset 1 (id:??) landed as
https://crrev.com/0c388aaf008fe3549e436fdfa3b2d2ee95b9a011
Cr-Commit-Position: refs/heads/master@{#340785}