Removing GetDefaultProfile from chrome/browser/net

BUG=322682
TEST=functionality is the same and it should be covered by existing tests

Review URL: https://codereview.chromium.org/105893008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@241452 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 241452