Revert of Add a has_media flag to VolumeMetadata.

Revert of Add a has_media flag to VolumeMetadata. (patchset #3 id:40001 of https://codereview.chromium.org/668013004/)

Reason for revert:
Suspected to have caused failure of test FileManagerPrivateApiTest.Mount

https://build.chromium.org/p/chromium.chromiumos/builders/Linux%20ChromiumOS%20Tests%20%28dbg%29%281%29/builds/33105

Original issue's description:
> Add a has_media flag to VolumeMetadata.
>
> The new flag carries the has_media status of a volume through from the DiskMountManager, so the information is available to chrome.fileManagerPrivate.onMountCompleted javascript listeners.
>
> BUG=420680
>
> Committed: https://crrev.com/7accfac4f10afbba205c87ca66a59c35775c695e
> Cr-Commit-Position: refs/heads/master@{#301144}

TBR=smckay@chromium.org,mkearney@chromium.org,mtomasz@chromium.org,kenobi@google.com,kenobi@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=420680
Committed: https://crrev.com/3c8c255f2d552ee1aca0d254e57eabdf7e056203
Cr-Commit-Position: refs/heads/master@{#301187}

[qyearsley, 2014-10-24 20:28:23]

Created Revert of Add a has_media flag to VolumeMetadata.

[commit-bot: I haz the power, 2014-10-24 20:29:04]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/673253005/1

[commit-bot: I haz the power, 2014-10-24 20:30:17]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-10-24 20:30:55]

Patchset 1 (id:??) landed as
https://crrev.com/3c8c255f2d552ee1aca0d254e57eabdf7e056203
Cr-Commit-Position: refs/heads/master@{#301187}