Bug 1560280 - Return a real userAgent string in Browser.getVersion. r=remote-protocol-reviewers,ato

Differential Revision: https://phabricator.services.mozilla.com/D35417

--HG--
extra : moz-landing-system : lando

remote/domains/parent/Browser.jsm

@@ -12,11 +12,13 @@ const {Domain} = ChromeUtils.import("chrome://remote/content/domains/Domain.jsm"
 class Browser extends Domain {
   getVersion() {
     const { isHeadless } = Cc["@mozilla.org/gfx/info;1"].getService(Ci.nsIGfxInfo);
+    const { userAgent } = Cc["@mozilla.org/network/protocol;1?name=http"]
+                            .getService(Ci.nsIHttpProtocolHandler);
     return {
       protocolVersion: "1",
       product: (isHeadless ? "Headless " : "") + "Firefox",
       revision: "1",
-      userAgent: "Firefox",
+      userAgent,
       jsVersion: "1.8.5",
     };
   }

remote/test/browser/browser_cdp.js

@@ -36,6 +36,7 @@ add_task(async function testCDP() {
   const version = await Browser.getVersion();
   const { isHeadless } = Cc["@mozilla.org/gfx/info;1"].getService(Ci.nsIGfxInfo);
   is(version.product, isHeadless ? "Headless Firefox" : "Firefox", "Browser.getVersion works and depends on headless mode");
+  is(version.userAgent, window.navigator.userAgent, "Browser.getVersion().userAgent is correct");
 
   // receive console.log messages and print them
   Log.enable();