Adds move assignment operator to scoped_refptr

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 ceee445216a3ce6af300c7830f19f528049e4c2c..df669121dcf77ecdc36b43e86906412e7d66e024 100644
--- a/webrtc/base/scoped_ref_ptr.h
+++ b/webrtc/base/scoped_ref_ptr.h
@@ -63,7 +63,7 @@
 #ifndef WEBRTC_BASE_SCOPED_REF_PTR_H_
 #define WEBRTC_BASE_SCOPED_REF_PTR_H_
 
-#include <stddef.h>
+#include <memory>
 
 namespace rtc {
 
@@ -134,6 +134,17 @@ class scoped_refptr {
     return *this = r.get();
   }
 
+  scoped_refptr<T>& operator=(scoped_refptr<T>&& r) {
+    scoped_refptr<T>(std::move(r)).swap(*this);

[Taylor Brandstetter, 2016/08/01 20:00:36]

I realize this uses the same method as Chromium's scoped_refptr, but do you know
why the std::move is used? Isn't `r` already movable, and so isn't this
std::move a no-op?

+    return *this;
+  }
+
+  template <typename U>
+  scoped_refptr<T>& operator=(scoped_refptr<U>&& r) {
+    scoped_refptr<T>(std::move(r)).swap(*this);
+    return *this;
+  }
+
   void swap(T** pp) {
     T* p = ptr_;
     ptr_ = *pp;