Chrome apps always use blue "native style" window frames on Linux.

This changes from the default style from Windows (which is designed to
look like Windows 8 windows). It makes V2 app windows look the same as
hosted app and other floating windows on Linux Aura.

Disabled --apps-use-native-frame flag on Linux (it now has no effect).

BUG=322256

Review URL: https://codereview.chromium.org/107723002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@241796 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 241796