Revert "Originally the initialization of window button's is done in FileManager"

The crrev.com/227265 revision broke the maximize/close button in gallery mode.
This CL revert it.

Original CL review: crrev.com/25992002

BUG=267281
TEST=manually

Review URL: https://codereview.chromium.org/26322006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@227505 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 227505