Used for testing NetInfov3 code in upcoming CL https://codereview.chromium.org/291203002

Design doc: https://docs.google.com/a/chromium.org/document/d/1LTk9uVMGi4kurzcF5ellsAJReTF31fFJMHrQwSVtBjc/

BUG=368358

Review URL: https://codereview.chromium.org/295003003

git-svn-id: svn://svn.chromium.org/blink/trunk@174718 bbb929c8-8fbe-4397-9dbb-9b2b20218538