Define iTunes location for media galleries tests.

chrome/browser/media_galleries/media_galleries_test_util.h

Index: chrome/browser/media_galleries/media_galleries_test_util.h
diff --git a/chrome/browser/media_galleries/media_galleries_test_util.h b/chrome/browser/media_galleries/media_galleries_test_util.h
index d18f7225ad4ae9641fb0382da5cc1b0f0b9fc577..9af5918be0e949348c5f467fc80d7b1e39162ffc 100644
--- a/chrome/browser/media_galleries/media_galleries_test_util.h
+++ b/chrome/browser/media_galleries/media_galleries_test_util.h
@@ -15,6 +15,7 @@ namespace extensions {
 class Extension;
 }
 
+class MockPreferences;
 class Profile;
 
 namespace chrome {
@@ -43,6 +44,10 @@ class EnsureMediaDirectoriesExists {
   scoped_ptr<base::ScopedPathOverride> pictures_override_;
   scoped_ptr<base::ScopedPathOverride> video_override_;
 
+#if defined(OS_MACOSX)
+  scoped_ptr<MockPreferences> mac_preferences_;
+#endif
+
   DISALLOW_COPY_AND_ASSIGN(EnsureMediaDirectoriesExists);
 };