Rename webrtc::StatsObserver to webrtc::CallStatsObserver
to avoid ODR violations with peerconnectioninterface.h in libjingle.

Conflict introduced in
https://webrtc-codereview.appspot.com/1060005/diff/14010/webrtc/modules/interface/module_common_types.h#newcode326

TEST=none
BUG=none

Review URL: https://webrtc-codereview.appspot.com/1105011

git-svn-id: http://webrtc.googlecode.com/svn/trunk/webrtc@3540 4adac7df-926f-26a2-2b94-8c16560cd09d
7 files changed