Add fieldtrial_testing_config for parallel downloading.

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 d750e452c05bbff4354485bb9925701a050bcbef..0b13e43fbe150c528855308bd0db0557b94a2259 100644
--- a/testing/variations/fieldtrial_testing_config.json
+++ b/testing/variations/fieldtrial_testing_config.json
@@ -1778,6 +1778,18 @@
             ]
         }
     ],
+    "ParallelDownloading": [
+        {
+            "platforms": [
+                "android"
+            ],
+            "experiments": [
+                {
+                    "name": "Enabled"
+                }
+            ]

[Alexei Svitkine (slow), 2017/04/19 19:56:21]

You're missing enable_features and params sections.

You'll need these to match your beta configs or you'll get warnings about that.

[xingliu, 2017/04/19 20:54:23]

Done.

+        }
+    ],
     "PassiveDocumentEventListeners": [
         {
             "platforms": [