This adds the onNetworkChanged event to networkingPrivate

chrome/common/extensions/api/networking_private.json

Index: chrome/common/extensions/api/networking_private.json
diff --git a/chrome/common/extensions/api/networking_private.json b/chrome/common/extensions/api/networking_private.json
index a56770941a829f8ba5324dbe55c3379304652f12..4a142e31b432840e9f4de70fb7475a06c1cbc7ce 100644
--- a/chrome/common/extensions/api/networking_private.json
+++ b/chrome/common/extensions/api/networking_private.json
@@ -99,6 +99,20 @@
           }
         ]
       }
+    ],
+    "events": [
+      {
+        "name": "onNetworkChanged",
+        "type": "function",
+        "description": "Fired when the properties change on any of the networks.  Only contains the networks that changed, but each item contains all the properties for the changed network.",
+        "parameters": [
+          {
+            "name": "changes",
+            "type": "array",
+            "items": { "$ref": "NetworkProperties" }
+          }
+        ]
+      }
     ]
   }
 ]