aura: Fix file-opening functions in platform_util.
This removes NOTIMPLEMENTED()s for platform_util's
ShowItemInFolder(), OpenItem(), and OpenExternal(). We now
use the native Chrome OS, Windows, or Linux versions of
these functions.
BUG=99712
TEST=manual: checked that we use the file manager extension to open downloaded files on Chrome OS and that we use XDG on linux
Review URL: http://codereview.chromium.org/8808003
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@113157 0039d316-1c4b-4281-b951-d872f2087c98
4 files changed
