Revert of Track the active ExtensionKeybindingRegistry and make it available to EventRewriter.

Revert of Track the active ExtensionKeybindingRegistry and make it available to EventRewriter. (patchset #22 id:480001 of https://codereview.chromium.org/553243002/)

Reason for revert:
The new tests fail on Linux Chromeos (ozone).

http://build.chromium.org/p/chromium.chromiumos/builders/Linux%20ChromiumOS%20Ozone%20Tests%20%282%29/builds/1998/steps/interactive_ui_tests/logs/ChromeOSConversions

Original issue's description:
> Track the active ExtensionKeybindingRegistry and make it available to EventRewriter.
>
> Add the ability to query globally if a shortcut
> is registered by an extension and use that to avoid unnecessarily rewriting
> Chrome OS keys.
>
> BUG=410944
>
> Committed: https://crrev.com/4264d2c4b5d217e1c5dbc2ae80ab6ce595f9b6d3
> Cr-Commit-Position: refs/heads/master@{#295284}

TBR=finnur@chromium.org,sky@chromium.org,rdevlin.cronin@chromium.org,dtseng@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=410944
Committed: https://crrev.com/5496d52ba9a1d3d8e033dcc5b2a8184626345a08
Cr-Commit-Position: refs/heads/master@{#295324}

[Elliot Glaysher, 2014-09-17 19:43:41]

Created Revert of Track the active ExtensionKeybindingRegistry and make it
available to EventRewriter.

[commit-bot: I haz the power, 2014-09-17 19:44:34]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patchset/575093003/1

[commit-bot: I haz the power, 2014-09-17 19:46:34]

Committed patchset #1 (id:1) as a148a7ff017e9d43755fe453ee61dc6acc93dfb5

[commit-bot: I haz the power, 2014-09-17 19:47:08]

Patchset 1 (id:??) landed as
https://crrev.com/5496d52ba9a1d3d8e033dcc5b2a8184626345a08
Cr-Commit-Position: refs/heads/master@{#295324}