Check that stats_proxy_ is non-NULL before use.
Check that stats_proxy_ is non-NULL before use.

BUG=None

Review-Url: https://codereview.webrtc.org/2451143002
Cr-Original-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#14788}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 784a83122bc837cbed500d6295b4b45f8fe6a7be

Alkalyne/webrtctrunk,Alkalyne/webrtctrunk,Alkalyne/webrtctrunk,Alkalyne/webrtctrunk,Alkalyne/webrtctrunk,Alkalyne/webrtctrunk,Alkalyne/webrtctrunk,Alkalyne/webrtctrunk