Fix gyp on OS X with use_goma=1.

build/toolchain/mac/BUILD.gn

Index: build/toolchain/mac/BUILD.gn
diff --git a/build/toolchain/mac/BUILD.gn b/build/toolchain/mac/BUILD.gn
index 7e552d6c1b3c7dc627f5c347244aac939dbe5c77..1ff00b22e8dad68b4892e96268ebcb063fe81a5f 100644
--- a/build/toolchain/mac/BUILD.gn
+++ b/build/toolchain/mac/BUILD.gn
@@ -6,6 +6,8 @@
 # some enhancements since the commands on Mac are slightly different than on
 # Linux.
 
+import("../goma.gni")

[brettw, 2014/01/18 22:04:52]

I've been trying to do absolute paths for imports like we do in C++
("//build/toolchain/goma.gni").

[Nico, 2014/01/18 22:06:03]

I'll try to remember :-) I cribbed this from toolchain/linux/BUILD.gn, which
also has a relative import at the moment.

+
 # Should only be running on Mac.
 assert(is_mac || is_ios)
 
@@ -18,7 +20,26 @@ if (is_clang) {
 
   # Set the GYP header for all toolchains when running under Clang.
   if (is_gyp) {
-    gyp_header = "'make_global_settings': [" + make_clang_global_settings + "],"
+    make_global_settings = make_clang_global_settings
+
+    if (use_goma) {
+      # There is a TODO(yyanagisawa) in common.gypi about the make generator not
+      # supporting CC_wrapper without CC. As a result, we must add a condition
+      # when on the generator when we're not explicitly setting the variables
+      # above (which happens when gyp_header is empty at this point).
+      #
+      # GYP will interpret the file once for each generator, so we have to write
+      # this condition into the GYP file since the user could have more than one
+      # generator set.
+      gyp_header =
+        "'conditions':" +
+        "[['\"<(GENERATOR)\"==\"ninja\"', { 'make_global_settings': [" +
+        make_global_settings +
+        make_goma_global_settings +
+        "]}]],"
+    } else {
+      gyp_header = "'make_global_settings': [" + make_global_settings + "],"
+    }
   }
 } else {
   cc = "gcc"