Clean up unnecessary codes when deleting a custom wallpaper

This part of code is useless (also harmless) when trying to delete a custom wallpaper in Wallpaper Picker App.
WallpaperManager.removeCustomWallpaper() does all the cleanup work so this part of code becames redundant.

This CL is split from https://codereview.chromium.org/1566713005 and has been lgtmed so land it directly.

BUG=None
TBR=bshe@chromium.org

Committed: https://crrev.com/24c4ddc037619b03e7712906ef3031ee4abcb030
Cr-Commit-Position: refs/heads/master@{#371538}

[xdai1, 2016-01-26 01:35:10]

Description was changed from

==========
Clean up unnecessary codes.

BUG=None
==========

to

==========
This part of code is useless (but harmless) when trying to delete a custom
wallpaper in Wallpaper Picker App. WallpaperManager.removeCustomWallpaper() does
all the cleanup work and this part of code is redundant. 

This CL is split from https://codereview.chromium.org/1566713005. 

BUG=None
TBR=bshe@chromium.org
==========

[xdai1, 2016-01-26 01:35:34]

The CQ bit was checked by xdai@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-01-26 01:37:38]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1627483002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1627483002/1

[commit-bot: I haz the power, 2016-01-26 02:13:23]

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

[commit-bot: I haz the power, 2016-01-26 02:13:23]

Dry run: This issue passed the CQ dry run.

[xdai1, 2016-01-26 18:00:23]

Description was changed from

==========
This part of code is useless (but harmless) when trying to delete a custom
wallpaper in Wallpaper Picker App. WallpaperManager.removeCustomWallpaper() does
all the cleanup work and this part of code is redundant. 

This CL is split from https://codereview.chromium.org/1566713005. 

BUG=None
TBR=bshe@chromium.org
==========

to

==========
This part of code is useless (also harmless) when trying to delete a custom
wallpaper in Wallpaper Picker App. 
WallpaperManager.removeCustomWallpaper() does all the cleanup work so this part
of code becames redundant. 

This CL is split from https://codereview.chromium.org/1566713005 and has been
lgtmed so land it directly.

BUG=None
TBR=bshe@chromium.org
==========

[xdai1, 2016-01-26 18:00:48]

The CQ bit was checked by xdai@chromium.org

[commit-bot: I haz the power, 2016-01-26 18:03:02]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1627483002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1627483002/1

[commit-bot: I haz the power, 2016-01-26 18:09:13]

Description was changed from

==========
This part of code is useless (also harmless) when trying to delete a custom
wallpaper in Wallpaper Picker App. 
WallpaperManager.removeCustomWallpaper() does all the cleanup work so this part
of code becames redundant. 

This CL is split from https://codereview.chromium.org/1566713005 and has been
lgtmed so land it directly.

BUG=None
TBR=bshe@chromium.org
==========

to

==========
This part of code is useless (also harmless) when trying to delete a custom
wallpaper in Wallpaper Picker App. 
WallpaperManager.removeCustomWallpaper() does all the cleanup work so this part
of code becames redundant. 

This CL is split from https://codereview.chromium.org/1566713005 and has been
lgtmed so land it directly.

BUG=None
TBR=bshe@chromium.org
==========

[commit-bot: I haz the power, 2016-01-26 18:09:14]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-01-26 18:11:54]

Description was changed from

==========
This part of code is useless (also harmless) when trying to delete a custom
wallpaper in Wallpaper Picker App. 
WallpaperManager.removeCustomWallpaper() does all the cleanup work so this part
of code becames redundant. 

This CL is split from https://codereview.chromium.org/1566713005 and has been
lgtmed so land it directly.

BUG=None
TBR=bshe@chromium.org
==========

to

==========
This part of code is useless (also harmless) when trying to delete a custom
wallpaper in Wallpaper Picker App.
WallpaperManager.removeCustomWallpaper() does all the cleanup work so this part
of code becames redundant.

This CL is split from https://codereview.chromium.org/1566713005 and has been
lgtmed so land it directly.

BUG=None
TBR=bshe@chromium.org

Committed: https://crrev.com/24c4ddc037619b03e7712906ef3031ee4abcb030
Cr-Commit-Position: refs/heads/master@{#371538}
==========

[commit-bot: I haz the power, 2016-01-26 18:11:55]

Patchset 1 (id:??) landed as
https://crrev.com/24c4ddc037619b03e7712906ef3031ee4abcb030
Cr-Commit-Position: refs/heads/master@{#371538}