New to Eclipse Mars (possibly Luna; I haven't checked), eclipse.ini is no longer in the Contents/MacOS folder of the Eclipse application package (and most Google results have that out-of-date information). It can now be found at Contents/Eclipse/eclipse.ini.
You can read about the "why" of this change in the bug fix notes. Basically because of new application signing requirements in Mac OS 10.9 and above, they could no longer keep it in the old location; only the executable is allowed in the Contents/MacOS folder.