[BackgroundSync] Declare RelyOnAndroidNetworkDetection experiment

Bug: 1051508
Change-Id: I7204e38b3542c322c67030435339a943d7a0c0a9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2054229
Commit-Queue: Rayan Kanso <rayankans@chromium.org>
Reviewed-by: Steven Holte <holte@chromium.org>
Cr-Commit-Position: refs/heads/master@{#743232}

testing/variations/fieldtrial_testing_config.json

@@ -1099,6 +1099,24 @@
             ]
         }
     ],
+    "BackgroundSync": [
+        {
+            "platforms": [
+                "android"
+            ],
+            "experiments": [
+                {
+                    "name": "RelyOnAndroidNetworkDetection",
+                    "params": {
+                        "rely_on_android_network_detection": "true"
+                    },
+                    "enable_features": [
+                        "RelyOnAndroidNetworkDetection"
+                    ]
+                }
+            ]
+        }
+    ],
     "BlinkLayoutNG": [
         {
             "platforms": [