Indicator as Clean Architecture

src/background/presenters/indicator.js

@@ -0,0 +1,12 @@
+export default class IndicatorPresenter {
+  indicate(enabled) {
+    let path = enabled
+      ? 'resources/enabled_32x32.png'
+      : 'resources/disabled_32x32.png';
+    return browser.browserAction.setIcon({ path });
+  }
+
+  onClick(listener) {
+    browser.browserAction.onClicked.addListener(listener);
+  }
+}

src/background/presenters/tab.js

@@ -2,4 +2,8 @@ export default class TabPresenter {
   create(url) {
     browser.tabs.create({ url, });
   }
+
+  onSelected(listener) {
+    browser.tabs.onActivated.addListener(listener);
+  }
 }