drive: Rewrite FileSystemTest to deal with local IDs properly

BUG=275270
TEST=unit_tests --gtest_filter="FileSystemTest.*"
R=kinaba@chromium.org

Review URL: https://codereview.chromium.org/26948005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@228604 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 228604