drive: Set modified/accessed date when creating a directory

Otherwise, locally created directory is shown as last modified in 31 Dec, 1969...

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

Review URL: https://codereview.chromium.org/151273003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@248833 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 248833