Chromeutils.RequestPerformanceMetrics() is now composed of two parts:
- calls content processes via IPDL to get their counters
- directly dispatch counters from the parent process
MozReview-Commit-ID: HlgcEOzkyAq
--HG--
extra : rebase_source : 60e81a27cd3a1bf1378e6b977529964507633b63