Capitalize background scripts

src/background/infrastructures/Notifier.js

@@ -0,0 +1,23 @@
+const NOTIFICATION_ID = 'vimvixen-update';
+
+export default class Notifier {
+  notify(title, message, onclick) {
+    const listener = (id) => {
+      if (id !== NOTIFICATION_ID) {
+        return;
+      }
+
+      onclick();
+
+      browser.notifications.onClicked.removeListener(listener);
+    };
+    browser.notifications.onClicked.addListener(listener);
+
+    return browser.notifications.create(NOTIFICATION_ID, {
+      'type': 'basic',
+      'iconUrl': browser.extension.getURL('resources/icon_48x48.png'),
+      title,
+      message,
+    });
+  }
+}