GitLab

Also:
- speed up re-copies the XP/xcopy case by skipping old files
- clean up output for re-copies in the robocopy case by ignoring "extra" files

NOTRY=true
BUG=none
TEST=none

Review URL: https://chromiumcodereview.appspot.com/10837096

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@149912 0039d316-1c4b-4281-b951-d872f2087c98