Split parts of //chrome/utility's BUILD.gn into //chrome/utility/safe_browsing/mac.

chrome/utility/safe_browsing/mac/crdmg.cc

Index: chrome/utility/safe_browsing/mac/crdmg.cc
diff --git a/chrome/utility/safe_browsing/mac/crdmg.cc b/chrome/utility/safe_browsing/mac/crdmg.cc
index 18a5ea1535de467b5b70d4971d046641e9ebcc83..6b5205f98fe744b0a0bd925124e6c353543e29a1 100644
--- a/chrome/utility/safe_browsing/mac/crdmg.cc
+++ b/chrome/utility/safe_browsing/mac/crdmg.cc
@@ -25,6 +25,12 @@
 #include "chrome/utility/safe_browsing/mac/read_stream.h"
 #include "chrome/utility/safe_browsing/mac/udif.h"
 
+extern "C" {

[Nico, 2016/09/09 20:45:44]

Maybe add some `// This executable is only supposed to work on 10.10+, so
unconditionally use these functions` type comment

[Robert Sesek, 2016/09/09 20:47:28]

Done.

+int mkdirat(int, const char *, mode_t);
+int openat(int, const char *, int, ...);
+int unlinkat(int, const char *, int);
+}
+
 namespace {
 
 // SafeDMG (crdmg) is a utility that can perform a list or extract operation