Remove CircularFileStream / replace it with CallSessionFileRotatingStream.

webrtc/base/filerotatingstream.h

Index: webrtc/base/filerotatingstream.h
diff --git a/webrtc/base/filerotatingstream.h b/webrtc/base/filerotatingstream.h
index 7f6bc50fa22c5ca6d9d539a3b55ac9e11354c08f..f3de14ede4e42b39cc1fb780e05f30d839f107ba 100644
--- a/webrtc/base/filerotatingstream.h
+++ b/webrtc/base/filerotatingstream.h
@@ -50,6 +50,8 @@ class FileRotatingStream : public StreamInterface {
                      size_t* written,
                      int* error) override;
   bool Flush() override;
+  // Returns the total file size currently used on disk.
+  bool GetSize(size_t* size) const override;
   void Close() override;
 
   // Opens the appropriate file(s). Call this before using the stream.