Revert of permissions: remove duplicates from request multiple at the Blink level

Revert of permissions: remove duplicates from request multiple at the Blink level (patchset #4 id:60001 of https://codereview.chromium.org/1360023005/ )

Reason for revert:
BUG=538717
Original issue's description:
> permissions: remove duplicates from request multiple at the Blink level
>
> Propogating this information all the way to PermissionManager so it can be handled there
> seems to be a waste of time and memory. It also adds a bunch of complexity to
> all PermissionManager implementations.
>
> Instead of this, handle all duplication at the Blink level so that chrome
> can focus on handling requests.
>
> BUG=516626
>
> Committed: https://crrev.com/b3d2e697dc79112379f96f0f34cf26b83227a737
> Cr-Commit-Position: refs/heads/master@{#352072}

TBR=mlamouri@chromium.org,lalitm@google.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=516626
Committed: https://crrev.com/274f94ac26b2c789770e9280295a4f7dc71a8be0
Cr-Commit-Position: refs/heads/master@{#352113}

[dmurph, 2015-10-02 20:16:25]

Created Revert of permissions: remove duplicates from request multiple at the
Blink level

[commit-bot: I haz the power, 2015-10-02 20:17:51]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1381353002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1381353002/1

[commit-bot: I haz the power, 2015-10-02 20:21:06]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-10-02 20:21:57]

Patchset 1 (id:??) landed as
https://crrev.com/274f94ac26b2c789770e9280295a4f7dc71a8be0
Cr-Commit-Position: refs/heads/master@{#352113}

[mlamouri (slow - plz ping), 2015-10-03 14:53:02]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/1381423002/ by mlamouri@chromium.org.

The reason for reverting is: Depending CL has relanded..