mac: Use the new close button asset instead of vector drawing.

This has the unfortunate side effect of making the close buttons red.
(Glen says he might reconsider the color if there's enough of an outcry.)

Move the infobar and findbar close buttons to the same close button asset used
on Windows (not red).

On the plus side, this reduces the number of files depending on the
molokocacao code.

xib changes:
DownloadShelf.xib, TabView.xib: Made the close button 18x18 instead of 16x16
FindBar.xib, InfoBar.xib: Made the close button a regular NSButton, gave its
                          cell the type ImageButtonCell.
FindBar.xib: Connected close button to the new closeButton_ outlet.

Parts based on a patch from Andrew Bonventre <andybons@chromium.org>

BUG=52468,98453,111101

Review URL: https://codereview.chromium.org/10914252

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@156712 0039d316-1c4b-4281-b951-d872f2087c98
11 files changed