Temporary interface change to StatsReport::Id.
Temporary interface change to StatsReport::Id.

This change is just to allow rolling into Chromium, update Chromium and then commit the actual change in WebRTC that requires the interface change. It allows using a StatsReport::Id object as a pointer (foo->Bar()), since in an upcoming change, Id objects will be pointers.

R=magjed@webrtc.org
BUG=2822

Review URL: https://webrtc-codereview.appspot.com/43689004

Cr-Original-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#8697}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 75b7f17c29565ac8ddba38c14239113ac471ca5a

dcpang/fatline-libjingle,dcpang/fatline-libjingle,sippet/talk,dcpang/fatline-libjingle,sippet/talk,sippet/talk,sippet/talk,sippet/talk,dcpang/fatline-libjingle,dcpang/fatline-libjingle