Bug 913260 (part 2) - Tweak ghost window reporters.  r=mccr8.

--HG--
extra : rebase_source : db98ac69096f942608ead78709265609593e85d6
Bug 913260 (part 3) - Formalize the concept of "distinguished amounts" in the memory reporter manager.  r=mccr8.

--HG--
extra : rebase_source : cc6f50d85f384ed665d44b2e8850618fd8a56fa5
Bug 913260 (part 4) - Use distinguished amounts for all the memory measurements done by telemetry.  r=mccr8.

--HG--
extra : rebase_source : 0e9db51b137770ba7db15a99a4ec1e87071d2f47