Revert of Add the chrome.fileSystem.onVolumeListChanged event.

Revert of Add the chrome.fileSystem.onVolumeListChanged event. (patchset #2 id:20001 of https://codereview.chromium.org/1135383002/)

Reason for revert:
Seems to break browser_tests failed interactive_ui_tests on
Linux Chromium OS ASan LSan Tests (1).

This CL was the best I could find in the blame list. Reverting as Chrome sheriff to see if it helps.

See https://build.chromium.org/p/chromium.memory/builders/Linux%20Chromium%20OS%20ASan%20LSan%20Tests%20%281%29/builds/1252

Original issue's description:
> Add the chrome.fileSystem.onVolumeListChanged event.
>
> This CL adds an event which notifies extension about changed list of volumes
> which can be requested via chrome.fileSystem.requestFileSystem.
>
> TEST=browser_tests: *OnVolumeListChanged*
> BUG=440674
>
> Committed: https://crrev.com/a1cc3a6222b0027a3fcf7cf31787950b0496b85f
> Cr-Commit-Position: refs/heads/master@{#330047}

TBR=benwells@chromium.org,mtomasz@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=440674
Committed: https://crrev.com/1edc0b3fad5ec31765b6a2435db84713ba46cdb6
Cr-Commit-Position: refs/heads/master@{#330064}

[henrika (OOO until Aug 14), 2015-05-15 08:35:16]

Created Revert of Add the chrome.fileSystem.onVolumeListChanged event.

[commit-bot: I haz the power, 2015-05-15 08:35:37]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1145563002/1

[commit-bot: I haz the power, 2015-05-15 08:36:21]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-05-15 08:37:01]

Patchset 1 (id:??) landed as
https://crrev.com/1edc0b3fad5ec31765b6a2435db84713ba46cdb6
Cr-Commit-Position: refs/heads/master@{#330064}