Add background.js

background.js

@@ -0,0 +1,40 @@
+"use strict";
+
+const WINDOWS_CHROME_UA =
+  "Mozilla/5.0 (Windows NT 10.0; Win64; x64) " +
+  "AppleWebKit/537.36 (KHTML, like Gecko) " +
+  "Chrome/140.0.0.0 Safari/537.36";
+
+browser.webRequest.onBeforeSendHeaders.addListener(
+  (details) => {
+    const requestHeaders = details.requestHeaders ?? [];
+    let foundUserAgent = false;
+
+    for (const header of requestHeaders) {
+      if (header.name.toLowerCase() === "user-agent") {
+        header.value = WINDOWS_CHROME_UA;
+        foundUserAgent = true;
+        break;
+      }
+    }
+
+    if (!foundUserAgent) {
+      requestHeaders.push({
+        name: "User-Agent",
+        value: WINDOWS_CHROME_UA
+      });
+    }
+
+    return { requestHeaders };
+  },
+  {
+    urls: [
+      "*://netflix.com/*",
+      "*://*.netflix.com/*"
+    ]
+  },
+  [
+    "blocking",
+    "requestHeaders"
+  ]
+);