[fsp] Move unmount unit tests to the operations directory.

[fsp] Move unmount unit tests to the operations directory.

Operations are tested outside of the ProvidedFileSystem class. This CL moves
the last operation which was tested in the deprecated way.

TEST=unit_tests: *FileSystemProviderOperations*Unmount
BUG=373165
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=273091

[mtomasz, 2014-05-27 07:46:47]

@kinaba: PTAL. This is a mechanical copy&paste. Thanks.

[kinaba, 2014-05-27 07:56:59]

lgtm

[mtomasz, 2014-05-27 07:57:10]

The CQ bit was checked by mtomasz@chromium.org

[commit-bot: I haz the power, 2014-05-27 07:57:29]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/mtomasz@chromium.org/301633003/1

[commit-bot: I haz the power, 2014-05-27 09:40:32]

FYI, CQ is re-trying this CL (attempt #1).
Please consider checking whether the failures are real,
and report flakes to chrome-troopers@google.com.
The failing builders are:
  linux_chromium_chromeos_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/linux_chromium_chrome...)

[commit-bot: I haz the power, 2014-05-27 10:53:42]

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

[commit-bot: I haz the power, 2014-05-27 10:53:43]

Try jobs failed on following builders:
  linux_chromium_chromeos_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/linux_chromium_chrome...)

[mtomasz, 2014-05-27 23:22:53]

The CQ bit was checked by mtomasz@chromium.org

[commit-bot: I haz the power, 2014-05-27 23:23:29]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/mtomasz@chromium.org/301633003/1

[commit-bot: I haz the power, 2014-05-28 00:39:40]

Change committed as 273091