Move almost all references from WebRtcSession to PeerConnection

WebRtcSession is being merged into PeerConnection, and to make the
code review easier this is the first step towards achieving that.

Bug: webrtc:8323
Change-Id: I33778e46f20cb14089dff4328947868e207476bd
Reviewed-on: https://webrtc-review.googlesource.com/8760
Commit-Queue: Steve Anton <steveanton@webrtc.org>
Reviewed-by: Taylor Brandstetter <deadbeef@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20413}
diff --git a/pc/statscollector.h b/pc/statscollector.h
index 568d1ee..5c90066 100644
--- a/pc/statscollector.h
+++ b/pc/statscollector.h
@@ -21,7 +21,6 @@
 #include "api/mediastreaminterface.h"
 #include "api/peerconnectioninterface.h"
 #include "api/statstypes.h"
-#include "pc/webrtcsession.h"
 
 namespace webrtc {
 
@@ -139,7 +138,7 @@
   // Raw pointer to the peer connection the statistics are gathered from.
   PeerConnection* const pc_;
   double stats_gathering_started_;
-  ProxyTransportMap proxy_to_transport_;
+  std::map<std::string, std::string> proxy_to_transport_;
 
   // TODO(tommi): We appear to be holding on to raw pointers to reference
   // counted objects?  We should be using scoped_refptr here.