Enable StopNonTimersInBackground experiment for field trial testing

Bug: 822954
Change-Id: I8668f4003bff3fa47e1b542884f81cf1e13bffad
Reviewed-on: https://chromium-review.googlesource.com/1147505Reviewed-by: Mark Pearson <mpearson@chromium.org>
Commit-Queue: Scott Haseley <shaseley@google.com>
Cr-Commit-Position: refs/heads/master@{#577392}

testing/variations/fieldtrial_testing_config.json

@@ -4058,6 +4058,21 @@
             ]
         }
     ],
+    "StopNonTimersInBackground": [
+        {
+            "platforms": [
+                "android"
+            ],
+            "experiments": [
+                {
+                    "name": "Experiment",
+                    "enable_features": [
+                        "stop-non-timers-in-background"
+                    ]
+                }
+            ]
+        }
+    ],
     "SuperfishInterstitial": [
         {
             "platforms": [