code: public void saveSettings() {
          mCallbacks.printOutput("Saving settings...");
          
          // Clear settings
          mCallbacks.saveExtensionSetting(scan.getSettingsNamespace() + SETTING_URL, null);
          
          // Store settings
          mCallbacks.printOutput("Saving URL: " + urlTextField.getText());
          mCallbacks.saveExtensionSetting(scan.getSettingsNamespace() + SETTING_URL, urlTextField.getText());
      }
docs: Save all configured settings