Use scoped_refptr for On(Add|Remove)Stream and OnDataChannel.

webrtc/base/scoped_ref_ptr.h

Index: webrtc/base/scoped_ref_ptr.h
diff --git a/webrtc/base/scoped_ref_ptr.h b/webrtc/base/scoped_ref_ptr.h
index a71c20ae324e0b806d7cda60ed76cd1fecb5a4b4..ceee445216a3ce6af300c7830f19f528049e4c2c 100644
--- a/webrtc/base/scoped_ref_ptr.h
+++ b/webrtc/base/scoped_ref_ptr.h
@@ -89,6 +89,12 @@ class scoped_refptr {
       ptr_->AddRef();
   }
 
+  // Move constructors.
+  scoped_refptr(scoped_refptr<T>&& r) : ptr_(r.release()) {}
+
+  template <typename U>
+  scoped_refptr(scoped_refptr<U>&& r) : ptr_(r.release()) {}
+
   ~scoped_refptr() {
     if (ptr_)
       ptr_->Release();