Revert of mac: Weakly link against the CoreBluetooth framework.

Revert of mac: Weakly link against the CoreBluetooth framework. (patchset #2 id:80001 of https://codereview.chromium.org/1101513003/)

Reason for revert:
The GN file wasn't formatted correctly.

http://build.chromium.org/p/chromium.mac/builders/Mac%20GN%20%28dbg%29/builds/8764/steps/compile/logs/stdio

Original issue's description:
> mac: Weakly link against the CoreBluetooth framework.
>
> In the OSX 10.10 SDK, CoreBluetooth became a top level framework. Previously,
> it was nested in IOBluetooth. In order for Chrome to run on OSes older than OSX
> 10.10, the top level CoreBluetooth framework must be weakly linked.
>
> BUG=463170
>
> Committed: https://crrev.com/9fde3e00865650009c7e85fcb7157719372b97a8
> Cr-Commit-Position: refs/heads/master@{#326705}

TBR=rsesek@chromium.org,keybuk@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=463170
Committed: https://crrev.com/b86c45ca4b1d84748a5543ee85fa1ba38c8ee677
Cr-Commit-Position: refs/heads/master@{#326708}

[erikchen, 2015-04-24 00:54:37]

Created Revert of mac: Weakly link against the CoreBluetooth framework.

[commit-bot: I haz the power, 2015-04-24 00:55:20]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1065453003/1

[commit-bot: I haz the power, 2015-04-24 00:56:21]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-24 00:57:15]

Patchset 1 (id:??) landed as
https://crrev.com/b86c45ca4b1d84748a5543ee85fa1ba38c8ee677
Cr-Commit-Position: refs/heads/master@{#326708}