Addon enabled when PB is by default

index.js

@@ -29,6 +29,7 @@ const { attachTo } = require("sdk/content/mod");
 const { ContextualIdentityService } = require("resource://gre/modules/ContextualIdentityService.jsm");
 const { getFavicon } = require("sdk/places/favicon");
 const { modelFor } = require("sdk/model/core");
+const prefService = require("sdk/preferences/service");
 const self = require("sdk/self");
 const { Style } = require("sdk/stylesheet/style");
 const tabs = require("sdk/tabs");
@@ -77,6 +78,7 @@ const ContainerService = {
       "createIdentity",
       "removeIdentity",
       "updateIdentity",
+      "getPreference",
     ];
 
     // Map of identities.
@@ -548,6 +550,16 @@ const ContainerService = {
     });
   },
 
+  // Preferences
+
+  getPreference(args) {
+    if (!("pref" in args)) {
+      return Promise.reject("getPreference must be called with pref argument.");
+    }
+
+    return Promise.resolve(prefService.get(args.pref));
+  },
+
   // Styling the window
 
   configureWindows() {

webextension/background.js

@@ -1,14 +1,23 @@
-browser.tabs.onCreated.addListener(tab => {
-  if (tab.incognito) {
-    disableAddon(tab.id);
-  }
-});
+browser.runtime.sendMessage({
+  method: "getPreference",
+  pref: "browser.privatebrowsing.autostart"
+}).then(pbAutoStart => {
 
-browser.tabs.query({}).then(tabs => {
-  for (let tab of tabs) { // eslint-disable-line prefer-const
-    if (tab.incognito) {
-      disableAddon(tab.id);
-    }
+  // We don't want to disable the addon if we are in auto private-browsing.
+  if (!pbAutoStart) {
+    browser.tabs.onCreated.addListener(tab => {
+      if (tab.incognito) {
+        disableAddon(tab.id);
+      }
+    });
+
+    browser.tabs.query({}).then(tabs => {
+      for (let tab of tabs) { // eslint-disable-line prefer-const
+        if (tab.incognito) {
+          disableAddon(tab.id);
+        }
+      }
+    }).catch(() => {});
   }
 }).catch(() => {});