Get content_unittests to link on the mac GN build.

printing/BUILD.gn

Index: printing/BUILD.gn
diff --git a/printing/BUILD.gn b/printing/BUILD.gn
index d035801419310612bfe216ce94d81632b5cf9998..80d70e49e8cb48612615b213eac5e3e16be0e15e 100644
--- a/printing/BUILD.gn
+++ b/printing/BUILD.gn
@@ -226,7 +226,8 @@ if (use_cups) {
     defines = [ "USE_CUPS" ]
 
     if (is_mac) {
-      ldflags = [ "$mac_sdk_path/usr/lib/libcups.dylib" ]
+      libs = [ "cups" ]
+      lib_dirs = [ "$mac_sdk_path/usr/lib" ]

[Dirk Pranke, 2015/07/31 19:58:34]

I think using ldflags was almost certainly wrong here, since the dependency
doesn't propagate correctly.

Do you see any downsides to using libs/lib_dirs instead?

[brettw, 2015/07/31 21:35:04]

Nope, that's what you're supposed to do.

     } else {
       libs = exec_script("cups_config_helper.py", [ "--libs-for-gn" ], "value")
     }