GitLab

This refactors GetDeviceIdentifier function into GetDeviceIdentifier
and GetSaltedString. GetSaltedString is a utility function that can
be used elsewhere.

Review URL: https://codereview.chromium.org/309963003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@274520 0039d316-1c4b-4281-b951-d872f2087c98