Define iTunes location for media galleries tests.

chrome/chrome_tests_unit.gypi

Index: chrome/chrome_tests_unit.gypi
diff --git a/chrome/chrome_tests_unit.gypi b/chrome/chrome_tests_unit.gypi
index 185bfcf19aa313d4de171bfc74e8d7cfa6caf6fc..5afc952a9a0dfb99de37fad62964746287374946 100644
--- a/chrome/chrome_tests_unit.gypi
+++ b/chrome/chrome_tests_unit.gypi
@@ -16,8 +16,8 @@
         'chrome_resources.gyp:chrome_strings',
         'chrome_resources.gyp:theme_resources',
         'common',
-        '../base/base.gyp:test_support_base',
         '../base/base.gyp:base_prefs_test_support',
+        '../base/base.gyp:test_support_base',
         '../components/components.gyp:sessions_test_support',
         '../content/content.gyp:content_app_both',
         '../content/content.gyp:test_support_content',
@@ -153,6 +153,8 @@
         'browser/policy/cloud/policy_builder.h',
         'browser/policy/mock_configuration_policy_provider.cc',
         'browser/policy/mock_configuration_policy_provider.h',
+        'browser/policy/preferences_mock_mac.cc',
+        'browser/policy/preferences_mock_mac.h',
         'browser/policy/test/local_policy_test_server.cc',
         'browser/policy/test/local_policy_test_server.h',
         'browser/prefs/pref_service_mock_builder.cc',
@@ -1069,8 +1071,6 @@
         'browser/policy/policy_path_parser_unittest.cc',
         'browser/policy/policy_service_impl_unittest.cc',
         'browser/policy/policy_statistics_collector_unittest.cc',
-        'browser/policy/preferences_mock_mac.cc',
-        'browser/policy/preferences_mock_mac.h',
         'browser/policy/preg_parser_win_unittest.cc',
         'browser/policy/registry_dict_win_unittest.cc',
         'browser/policy/url_blacklist_manager_unittest.cc',