Converting hostname to login title: the PSL approach

foo.diff

commit d67700eadc05178d275d526bd696f2dacaf83221
Author: Jared Hirsch <ohai@6a68.net>
Date:   Tue Jan 22 16:21:23 2019 -0800

    Add Logins API utility method to get domain name, minus TLD, from a URL

diff --git a/src/experiments/logins/api.js b/src/experiments/logins/api.js
index 15dbf53..71412a2 100644
--- a/src/experiments/logins/api.js
+++ b/src/experiments/logins/api.js
@@ -128,6 +128,23 @@ this.logins = class extends ExtensionAPI {
               throw new ExtensionError(ex);
             }
           },
+          getDomain(url) {
+            let uri, domain;
+            try {
+              uri = Services.io.newURI(url);
+            } catch (ex) {
+              throw new ExtensionError(`getDomain failed: could not create nsIURI from ${url}: ${ex.message}`);
+            }
+            try {
+              const baseDomain = Services.eTLD.getBaseDomain(uri);
+              const suffix = Services.eTLD.getPublicSuffix(uri);
+              // Subtract the suffix ("com") plus one char for the leading dot.
+              domain = baseDomain.substring(0, baseDomain.length - (suffix.length + 1));
+            } catch (ex) {
+              throw new ExtensionError(`getDomain failed: could not extract domain from ${url}: ${ex.message}`);
+            }
+            return domain;
+          },
           onAdded: new EventManager(context, "logins.onAdded", fire => {
             const callback = (value) => {
               fire.async(value);
diff --git a/src/experiments/logins/schema.json b/src/experiments/logins/schema.json
index 9be90f0..0469468 100644
--- a/src/experiments/logins/schema.json
+++ b/src/experiments/logins/schema.json
@@ -260,6 +260,17 @@
           "type": "string",
           "description": "The ID of the Login to be removed."
         }]
+      },
+      {
+        "name": "getDomain",
+        "type": "function",
+        "description": "Given a URL as a string, strips out the TLD and returns just the base domain. Throws if the input URL is invalid.",
+        "async": true,
+        "parameters": [{
+          "name": "url",
+          "type": "string",
+          "description": "The URL to be parsed."
+        }]
       }
     ]
   }