Revert "Make the sandbox code link with the 10.7 SDK."

sandbox/mac/BUILD.gn

Index: sandbox/mac/BUILD.gn
diff --git a/sandbox/mac/BUILD.gn b/sandbox/mac/BUILD.gn
index 53e429d0c0e8bd5f2190fabcb4fc8a5c09560f91..3833b8a608af68e799c234be639367af555b57cb 100644
--- a/sandbox/mac/BUILD.gn
+++ b/sandbox/mac/BUILD.gn
@@ -32,11 +32,11 @@ component("sandbox") {
     "//base",
   ]
 
-  # When the build SDK is earlier than 10.8, generate a dynamic stub loader.
-  # When the SDK is higher, then libxpc.dylib will be loaded automatically as
-  # part of libSystem, and only forward declarations of private symbols are
+  # When the build SDK is 10.6, generate a dynamic stub loader. When the
+  # SDK is higher, then libxpc.dylib will be loaded automatically as part
+  # of libSystem, and only forward declarations of private symbols are
   # necessary.
-  if (mac_sdk_version < "10.8") {
+  if (mac_sdk_version == "10.6") {
     deps += [ ":generate_stubs" ]
   }
 }