Add Precache global ranking config to test list.

testing/variations/fieldtrial_testing_config.json

Index: testing/variations/fieldtrial_testing_config.json
diff --git a/testing/variations/fieldtrial_testing_config.json b/testing/variations/fieldtrial_testing_config.json
index a6b16ab4a5c56e97ffb02a240f74bec54fce5d38..d1241232c3fdb7ada449fd85262942c77b45ebf4 100644
--- a/testing/variations/fieldtrial_testing_config.json
+++ b/testing/variations/fieldtrial_testing_config.json
@@ -1464,6 +1464,12 @@
             "experiments": [
                 {
                     "name": "Enabled"
+                },
+                {
+                    "name": "EnabledGlobalRanking",

[Alexei Svitkine (slow), 2016/12/13 20:41:59]

Actually, put this first or remove the Enabled group.

The first config is what receives the test coverage.

[twifkak, 2016/12/13 20:43:16]

Oh, well the first config is what is being run on 1% of stable, so I'd prefer
that to be covered.

+                    "params": {
+                        "config_url": "https://www.gstatic.com/chrome/wifiprefetch/precache_config_gm"
+                    }
                 }
             ]
         }