Revert of Hook up the Push API with GCM's new ability to own encryption keys.

Revert of Hook up the Push API with GCM's new ability to own encryption keys. (patchset #6 id:160001 of https://codereview.chromium.org/1231613005/)

Reason for revert:
I broke the build. Sorry!

http://build.chromium.org/p/chromium.linux/builders/Linux%20GN%20Clobber/builds/3129/steps/compile/logs/stdio#error1

Original issue's description:
> Hook up the Push API with GCM's new ability to own encryption keys.
>
> This CL finishes implementing propagation of the "curve25519dh" attribute
> of the PushSubscription interface of the Push API. The public key will be
> provided by the GCM Driver, which internally uses the (new) GCMKeyStore.
>
> Encrypted messages cannot yet be received by GCM - that work remains. The
> functionality introduced in this CL is also still guarded behind the
> "--enable-push-message-payload" command line flag.
>
> BUG=486040
>
> Committed: https://crrev.com/23695aaa72c3c7c5176456c5ca4d3f7617be42fd
> Cr-Commit-Position: refs/heads/master@{#340263}

TBR=fgorski@chromium.org,jianli@chromium.org,johnme@chromium.org,thakis@chromium.org,avi@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=486040
Committed: https://crrev.com/8abc01b225df94c4f1b614319ae786623f328ef5
Cr-Commit-Position: refs/heads/master@{#340268}

[Peter Beverloo, 2015-07-24 13:15:39]

Created Revert of Hook up the Push API with GCM's new ability to own encryption
keys.

[commit-bot: I haz the power, 2015-07-24 13:15:56]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1259613002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1259613002/1

[commit-bot: I haz the power, 2015-07-24 13:16:51]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-07-24 13:17:31]

Patchset 1 (id:??) landed as
https://crrev.com/8abc01b225df94c4f1b614319ae786623f328ef5
Cr-Commit-Position: refs/heads/master@{#340268}