Revert of mac: Add auto-close and share-read-only functionality to SharedMemory.

Revert of mac: Add auto-close and share-read-only functionality to SharedMemory. (patchset #5 id:80001 of https://codereview.chromium.org/1418113003/ )

Reason for revert:
New unit-tests failing on 10.8

http://build.chromium.org/p/chromium.mac/builders/Mac10.8%20Tests/builds/10139/steps/base_unittests/logs/SharedMemoryMacMultiProcessTest.MachShareToProcessReadonly

Original issue's description:
> mac: Add auto-close and share-read-only functionality to Mach based SharedMemory.
>
> base::FileDescriptor has a property |auto_close| that is used to indicate that
> when the object is passed to an IPC message, the message takes ownership of the
> underlying OS handle. Since SharedMemoryHandle needs to be interchangeable with
> base::FileDescriptor, I added a property with similar functionality named
> |ownership_passes_to_ipc_|.
>
> The method ShareToProcess() is used to lower the current and maximum protection
> of the underlying OS handle before it is transferred to a different process. I
> implemented this functionality for Mach memory objects.
>
> BUG=535711
>
> Committed: https://crrev.com/033bbbcb63cab781552dfb435c035131c423de30
> Cr-Commit-Position: refs/heads/master@{#355880}

TBR=mark@chromium.org,tsepez@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=535711
Committed: https://crrev.com/160caaaf74aa406be6acf71b274583d30fa07552
Cr-Commit-Position: refs/heads/master@{#355908}

[erikchen, 2015-10-23 22:29:53]

Created Revert of mac: Add auto-close and share-read-only functionality to
SharedMemory.

[commit-bot: I haz the power, 2015-10-23 22:30:23]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1421933002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1421933002/1

[commit-bot: I haz the power, 2015-10-23 22:32:36]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1421933002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1421933002/1

[commit-bot: I haz the power, 2015-10-23 22:34:08]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-10-23 22:35:00]

Patchset 1 (id:??) landed as
https://crrev.com/160caaaf74aa406be6acf71b274583d30fa07552
Cr-Commit-Position: refs/heads/master@{#355908}