drive: Add ClientContext argument to JobScheduler::AddNewDirectory

Add ClientContext argument.
Remove JobScheduler::CreateFile.

BUG=244348,340553
TEST=unit_tests
R=kinaba@chromium.org

Review URL: https://codereview.chromium.org/153513002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@248835 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 248835