Fix bustage

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@247634 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 247634
Fix platform checks in Clipboard.

Ozone uses clipboard_aura and DChecks in WriteObjects with type
CLIPBOARD_TYPE_SELECTION fail here as this is defined only for X11 
platform. This CL replaces the current platform checks(X11) with 
checks this shouldn't be defined on.

Review URL: https://codereview.chromium.org/148153016

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@247635 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 247635