Revert of Remove a scoped_refptr<>::swap overload

base/memory/ref_counted.h

Index: base/memory/ref_counted.h
diff --git a/base/memory/ref_counted.h b/base/memory/ref_counted.h
index 9c9aea12e83784509d851c5e67e8da1291b34695..ff46e6d6e5a9c87782b449474fbbebc4e0865454 100644
--- a/base/memory/ref_counted.h
+++ b/base/memory/ref_counted.h
@@ -7,7 +7,6 @@
 
 #include <stddef.h>
 
-#include <algorithm>
 #include <cassert>
 #include <iosfwd>
 #include <type_traits>
@@ -355,7 +354,15 @@
     return *this;
   }
 
-  void swap(scoped_refptr<T>& r) { std::swap(ptr_, r.ptr_); }
+  void swap(T** pp) {
+    T* p = ptr_;
+    ptr_ = *pp;
+    *pp = p;
+  }
+
+  void swap(scoped_refptr<T>& r) {
+    swap(&r.ptr_);
+  }
 
   explicit operator bool() const { return ptr_ != nullptr; }