Create a mechanism define declarative rules via the extension manifest.

chrome/common/extensions/api/_manifest_features.json

Index: chrome/common/extensions/api/_manifest_features.json
diff --git a/chrome/common/extensions/api/_manifest_features.json b/chrome/common/extensions/api/_manifest_features.json
index 201815014165f4f1211dc02c32cd9c56f2bcc7ad..60ca1e766db431d6dd6e8bbec038dda7a512602b 100644
--- a/chrome/common/extensions/api/_manifest_features.json
+++ b/chrome/common/extensions/api/_manifest_features.json
@@ -96,6 +96,10 @@
     ],
     "no_doc": true
   },
+  "event_rules": {
+    "channel": "stable",

[not at google - send to devlin, 2015/06/04 17:58:48]

Note to readers (no action needed): I don't think it's necessary to start this
in dev channel, it doesn't grant capabilities.

[danduong, 2015/06/04 19:56:07]

Acknowledged.

+    "extension_types": "all"

[not at google - send to devlin, 2015/06/04 17:58:48]

"all" is scary, but the right thing in this case. Could you add a comment here:

// "event_rules" does not grant any capabilities, it's just
// an optimisation for any API which uses events, so it's safe
// to expose to all extension types.
"extension_types": "all"

[danduong, 2015/06/04 19:10:58]

Done.

+  },
   "devtools_page": {
     "channel": "stable",
     "extension_types": ["extension", "legacy_packaged_app"]