Revert of Include MTP devices in Cloud Import happiness.

Revert of Include MTP devices in Cloud Import happiness. (patchset #9 id:160001 of https://codereview.chromium.org/778123006/)

Reason for revert:
seems to be causing crashes on chrome os:

https://build.chromium.org/p/chromium.chromiumos/builders/Linux%20ChromiumOS%20Tests%20%281%29/builds/53530
https://build.chromium.org/p/chromium.chromiumos/builders/Linux%20ChromiumOS%20Tests%20%28dbg%29%281%29/builds/35254

Original issue's description:
> Include MTP devices in Cloud Import happiness.
> Nuke "VolumeManager.isType".
> Add test coverage of importer_common methods.
> Make all "DCIM" dir-name matching case-insensitive.
>
> BUG=420680
> TEST=browser_test: FileManagerJsTest.*
>
> Committed: https://crrev.com/15d1aae4da7783607df3fac2d38198e817cf6fa0
> Cr-Commit-Position: refs/heads/master@{#308414}

TBR=mtomasz@chromium.org,smckay@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=420680
Committed: https://crrev.com/455f193f3912bbd7d678fb36a2165629931ee7ab
Cr-Commit-Position: refs/heads/master@{#308442}

[samuong, 2014-12-15 22:24:28]

Created Revert of Include MTP devices in Cloud Import happiness.

[commit-bot: I haz the power, 2014-12-15 22:25:50]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/807583003/1

[commit-bot: I haz the power, 2014-12-15 22:27:04]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-12-15 22:27:46]

Patchset 1 (id:??) landed as
https://crrev.com/455f193f3912bbd7d678fb36a2165629931ee7ab
Cr-Commit-Position: refs/heads/master@{#308442}