Revert of [Mac] Remove unnecessary button on 'Bookmark all tabs' window

Revert of [Mac] Remove unnecessary button on 'Bookmark all tabs' window (patchset #2 id:20001 of https://codereview.chromium.org/583633002/)

Reason for revert:
Nonono you can't just hack out lines from xib files! https://codereview.chromium.org/586543002/ rebuilds the xib file in Xcode to accomplish this and more.

Original issue's description:
> [Mac] Remove unnecessary button on 'Bookmark all tabs' window
>
> Remove unnecessary button on 'Bookmark all tabs' window which appears
> before "Bookmarks Bar"
> XIB Changes:
> Removing the line in the following .xib file which is responsible for the appearance of empty button.
> chrome/app/nibs/BookmarkAllTabs.xib
>
> BUG=415554
> R=asvitkine@chromium.org
>
> TEST=
> 1) Launch chrome, open 2-3 tabs.
> 2) Right click on last tab and select 'Bookmark all tabs'
> 3) Empty button shouldn't be shown.
>
> Committed: https://crrev.com/0ce925fc1ee0f53142313d1b63b32dafbeeeaace
> Cr-Commit-Position: refs/heads/master@{#295714}

TBR=asvitkine@chromium.org,shilpa.shri@samsung.com
NOTREECHECKS=true
NOTRY=true
BUG=415554
Committed: https://crrev.com/d9ab67759f6cd14a7f323a2134b6982f2dc7ed10
Cr-Commit-Position: refs/heads/master@{#295976}

[Avi (use Gerrit), 2014-09-22 15:47:52]

Created Revert of [Mac] Remove unnecessary button on 'Bookmark all tabs' window

[commit-bot: I haz the power, 2014-09-22 15:49:18]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/592833002/1

[commit-bot: I haz the power, 2014-09-22 15:50:05]

Committed patchset #1 (id:1) as 45afabe044d20154947a4da8301067a6178afdd4

[commit-bot: I haz the power, 2014-09-22 15:50:37]

Patchset 1 (id:??) landed as
https://crrev.com/d9ab67759f6cd14a7f323a2134b6982f2dc7ed10
Cr-Commit-Position: refs/heads/master@{#295976}