Update createRemoteChild to pass SandboxFlags

Update createRemoteChild to pass SandboxFlags.

Until now, the FrameOwner for remote frames with a remote parent was a PlaceholderFrameOwner, which couldn't store sandbox flags.  The Blink side of this CL replaces PlaceholderFrameOwner with a RemoteBridgeFrameOwner, which does store sandbox flags, and with this change, we will initialize them using the replicated state that's already passed in to CreateFrameProxy.

Corresponding Blink patch (needs to land first): https://codereview.chromium.org/910313004/

BUG=426512
Committed: https://crrev.com/81a14d049fd77caf3b5f97cdf446f31a500b5bad
Cr-Commit-Position: refs/heads/master@{#316604}

[alexmos, 2015-02-11 22:58:43]

alexmos@chromium.org changed reviewers:
+ creis@chromium.org

[alexmos, 2015-02-11 23:02:05]

Charlie, could you please review this really small CL?

[Charlie Reis, 2015-02-11 23:19:34]

LGTM

[alexmos, 2015-02-13 15:05:52]

The CQ bit was checked by alexmos@chromium.org

[commit-bot: I haz the power, 2015-02-13 15:06:45]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/886923004/1

[commit-bot: I haz the power, 2015-02-13 16:11:27]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-02-13 16:11:28]

Try jobs failed on following builders:
  linux_chromium_chromeos_rel_ng on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[alexmos, 2015-02-17 17:58:25]

The CQ bit was checked by alexmos@chromium.org

[commit-bot: I haz the power, 2015-02-17 17:59:18]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/886923004/1

[commit-bot: I haz the power, 2015-02-17 17:59:54]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-02-17 18:00:40]

Patchset 1 (id:??) landed as
https://crrev.com/81a14d049fd77caf3b5f97cdf446f31a500b5bad
Cr-Commit-Position: refs/heads/master@{#316604}