Create a mechanism define declarative rules via the extension manifest.

chrome/common/extensions/docs/templates/json/manifest.json

 {
   "app": {
     "documentation": "manifest/app",
     "example": {},
     "level": "required"
   },
   "app.background": {
     "example": {"scripts": ["background.js"]},
     "level": "required"
   },
@@ skipping 52 matching lines @@
   },
   "description": {
     "documentation": "manifest/description",
     "example": "A plain text description",
     "level": "recommended"
   },
   "devtools_page": {
     "documentation": "devtools",
     "example": "devtools.html"
   },
+  "event_rules": {
+    "documentation": "manifest/event_rules",
+    "example": [{}]
+  },
   "export": {
     "documentation": "shared_modules",
     "example": {}
   },
   "externally_connectable": {
     "documentation": "manifest/externally_connectable",
     "example": {
       "matches": ["*://*.example.com/*"]
     }
   },
@@ skipping 156 matching lines @@
   },
   "web_accessible_resources": {
     "documentation": "manifest/web_accessible_resources",
     "example": []
   },
   "webview": {
     "documentation": "tags/webview#local_resources",
     "example": {}
   }
 }