Indicator shows the add-on enabled

src/background/components/indicator.js

@@ -0,0 +1,38 @@
+import * as indicators from '../shared/indicators';
+import messages from 'shared/messages';
+
+export default class IndicatorComponent {
+  constructor(store) {
+    this.store = store;
+
+    messages.onMessage(this.onMessage.bind(this));
+
+    browser.tabs.onActivated.addListener((info) => {
+      return browser.tabs.query({ currentWindow: true }).then(() => {
+        return this.onTabActivated(info);
+      });
+    });
+  }
+
+  onTabActivated(info) {
+    return browser.tabs.sendMessage(info.tabId, {
+      type: messages.ADDON_ENABLED_QUERY,
+    }).then((resp) => {
+      return this.updateIndicator(resp.enabled);
+    });
+  }
+
+  onMessage(message) {
+    switch (message.type) {
+    case messages.ADDON_ENABLED_RESPONSE:
+      return this.updateIndicator(message.enabled);
+    }
+  }
+
+  updateIndicator(enabled) {
+    if (enabled) {
+      return indicators.enable();
+    }
+    return indicators.disable();
+  }
+}

src/background/index.js

@@ -3,6 +3,7 @@ import messages from 'shared/messages';
 import BackgroundComponent from 'background/components/background';
 import OperationComponent from 'background/components/operation';
 import TabComponent from 'background/components/tab';
+import IndicatorComponent from 'background/components/indicator';
 import reducers from 'background/reducers';
 import { createStore } from 'shared/store';
 import * as versions from 'shared/versions';
@@ -16,12 +17,13 @@ const store = createStore(reducers, (e, sender) => {
     });
   }
 });
-// eslint-disable-next-line no-unused-vars
+
+/* eslint-disable no-unused-vars */
 const backgroundComponent = new BackgroundComponent(store);
-// eslint-disable-next-line no-unused-vars
 const operationComponent = new OperationComponent(store);
-// eslint-disable-next-line no-unused-vars
 const tabComponent = new TabComponent(store);
+const indicatorComponent = new IndicatorComponent(store);
+/* eslint-enable no-unused-vars */
 
 store.dispatch(settingActions.load());
 

src/background/shared/indicators.js

@@ -0,0 +1,13 @@
+const enable = () => {
+  return browser.browserAction.setIcon({
+    path: 'resources/enabled_32x32.png',
+  });
+};
+
+const disable = () => {
+  return browser.browserAction.setIcon({
+    path: 'resources/disabled_32x32.png',
+  });
+};
+
+export { enable, disable };