allow the admin to alter the default user-agent string

extension/common.js

@@ -21,6 +21,7 @@ const prefs = {
   parser: {}, // maps ua string to a ua object,
   log: false
 };
+window.prefs = prefs; // access from popup
 
 const log = (...args) => prefs.log && console.log(...args);
 
@@ -40,11 +41,20 @@ expand.rules = {};
 
 chrome.storage.local.get(prefs, ps => {
   Object.assign(prefs, ps);
-  expand();
-  chrome.tabs.query({}, ts => {
-    ts.forEach(t => tabs[t.id] = t.windowId);
-    ua.update();
+  // update prefs.ua from the managed storage
+  chrome.storage.managed.get({
+    ua: ''
+  }, rps => {
+    if (!chrome.runtime.lastError && rps.ua) {
+      prefs.ua = rps.ua;
+    }
+    expand();
+    chrome.tabs.query({}, ts => {
+      ts.forEach(t => tabs[t.id] = t.windowId);
+      ua.update();
+    });
   });
+
   if (chrome.browserAction.setBadgeBackgroundColor) { // FF for Android
     chrome.browserAction.setBadgeBackgroundColor({
       color: prefs.color

extension/data/popup/index.js

@@ -156,7 +156,6 @@ document.addEventListener('DOMContentLoaded', () => fetch('./map.json').then(r =
   document.querySelector('#os optgroup:last-of-type').appendChild(f2);
 
   chrome.storage.local.get({
-    'ua': '',
     'popup-browser': 'Chrome',
     'popup-os': 'Windows',
     'popup-sort': 'descending'
@@ -165,10 +164,12 @@ document.addEventListener('DOMContentLoaded', () => fetch('./map.json').then(r =
     document.getElementById('os').value = prefs['popup-os'];
     document.getElementById('sort').value = prefs['popup-sort'];
 
-    const ua = prefs.ua || navigator.userAgent;
-    update(ua);
-    document.getElementById('ua').value = ua;
-    document.getElementById('ua').dispatchEvent(new Event('input'));
+    chrome.runtime.getBackgroundPage(bg => {
+      const ua = bg.prefs.ua || navigator.userAgent;
+      update(ua);
+      document.getElementById('ua').value = ua;
+      document.getElementById('ua').dispatchEvent(new Event('input'));
+    });
   });
 }));
 

extension/manifest.json

@@ -28,6 +28,9 @@
     "128": "data/icons/active/128.png",
     "256": "data/icons/active/256.png"
   },
+  "storage": {
+    "managed_schema": "schema.json"
+  },
   "background":{
     "scripts":[
       "ua-parser.min.js",

extension/schema.json

@@ -0,0 +1,9 @@
+{
+  "type": "object",
+  "properties": {
+    "ua": {
+      "title": "Custom User-Agent String",
+      "type": "string"
+    }
+  }
+}