Move CreateSocketPair to header file

base/posix/unix_domain_socket_linux.h

Index: base/posix/unix_domain_socket_linux.h
diff --git a/base/posix/unix_domain_socket_linux.h b/base/posix/unix_domain_socket_linux.h
index 2ba739e1083f9a40d38e402a34da2689327d74b7..84e7d16009385870a025724d9b46bccd9982e892 100644
--- a/base/posix/unix_domain_socket_linux.h
+++ b/base/posix/unix_domain_socket_linux.h
@@ -19,6 +19,13 @@ namespace base {
 
 class Pickle;
 
+#if !defined(OS_NACL_NONSFI)
+// Creates a connected pair of UNIX-domain SOCK_SEQPACKET sockets, and passes
+// ownership of the newly allocated file descriptors to |one| and |two|.
+// Returns true on success.
+bool BASE_EXPORT CreateSocketPair(ScopedFD* one, ScopedFD* two);
+#endif
+
 class BASE_EXPORT UnixDomainSocket {
  public:
   // Maximum number of file descriptors that can be read by RecvMsg().