I just adding an existing project to GitHub using the command line.
Sometimes eclipse shows the branch in the package view like:
foo [foo master]
If your imported project into Eclipse workspace is a git repo, you can Share your project with Git
If without creating a new repo, the act of selecting
File > Team > Share Project and then
Git should be enough for Eclipse to reconsider how it display your project in the Package Explorer (ie with git information on it)
If this does not work, the alternate approach would be to: