Don't delete UMA observer until after PeerConnection.

content/renderer/media/rtc_peer_connection_handler.h

Index: content/renderer/media/rtc_peer_connection_handler.h
diff --git a/content/renderer/media/rtc_peer_connection_handler.h b/content/renderer/media/rtc_peer_connection_handler.h
index cc179dcd339e2cd1333c93a83a83479c5e466961..0ad099fe4cc9197d24a78e7d57fd8087679ecf5a 100644
--- a/content/renderer/media/rtc_peer_connection_handler.h
+++ b/content/renderer/media/rtc_peer_connection_handler.h
@@ -262,9 +262,10 @@ class CONTENT_EXPORT RTCPeerConnectionHandler
   int num_local_candidates_ipv4_ = 0;
   int num_local_candidates_ipv6_ = 0;
 
-  // To make sure the observer is released after the native_peer_connection_,
-  // it has to come first.
+  // To make sure the observers are released after native_peer_connection_,
+  // they have to come first.
   scoped_refptr<Observer> peer_connection_observer_;
+  scoped_refptr<webrtc::UMAObserver> uma_observer_;
 
   // |native_peer_connection_| is the libjingle native PeerConnection object.
   scoped_refptr<webrtc::PeerConnectionInterface> native_peer_connection_;
@@ -284,7 +285,6 @@ class CONTENT_EXPORT RTCPeerConnectionHandler
   std::map<webrtc::MediaStreamInterface*,
            std::unique_ptr<content::RemoteMediaStreamImpl>>
       remote_streams_;
-  scoped_refptr<webrtc::UMAObserver> uma_observer_;
   base::TimeTicks ice_connection_checking_start_;
 
   // Track which ICE Connection state that this PeerConnection has gone through.