Revert of Files.app: Split background.js

Revert of Files.app: Split background.js (patchset #4 id:60001 of https://codereview.chromium.org/562103002/)

Reason for revert:
This patch breaks the test.

Original issue's description:
> Files.app: Split background.js
>
> This patch splits the background.js into the 3 files (background_base.js, app_window_wrapper.js, background.js), extracting the common classes.
>
> This patch itself doesn't change any functionality, but the extracted files will be used in the separated audio player app in near future.
>
> BUG=375039
> TEST=browser_test passes
>
> Committed: https://crrev.com/479878c12c436c0bec667483df29fe1f23b710a2
> Cr-Commit-Position: refs/heads/master@{#294998}

TBR=hirono@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=375039
Committed: https://crrev.com/326fdba9410033d6d49d4d36ee44818e6a6e8a80
Cr-Commit-Position: refs/heads/master@{#295019}

[yoshiki, 2014-09-16 06:23:36]

Created Revert of Files.app: Split background.js

[commit-bot: I haz the power, 2014-09-16 06:23:51]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patchset/563743004/1

[yoshiki, 2014-09-16 06:24:46]

yoshiki@chromium.org changed reviewers:
- hirono@chromium.org

[commit-bot: I haz the power, 2014-09-16 06:24:48]

Committed patchset #1 (id:1) as 547da497a4fc771e9f4888653ab27ee9f65bf80e

[commit-bot: I haz the power, 2014-09-16 06:26:05]

Patchset 1 (id:??) landed as
https://crrev.com/326fdba9410033d6d49d4d36ee44818e6a6e8a80
Cr-Commit-Position: refs/heads/master@{#295019}