--- a/browser/tools/mozscreenshots/mozscreenshots/extension/configurations/PermissionPrompts.jsm
+++ b/browser/tools/mozscreenshots/mozscreenshots/extension/configurations/PermissionPrompts.jsm
@@ -15,17 +15,16 @@ Cu.import("resource://testing-common/Con
 Cu.import("resource://testing-common/BrowserTestUtils.jsm");
 
 const URL = "https://test1.example.com/extensions/mozscreenshots/browser/chrome/mozscreenshots/lib/permissionPrompts.html";
 let lastTab = null;
 
 this.PermissionPrompts = {
   init(libDir) {
     Services.prefs.setBoolPref("media.navigator.permission.fake", true);
-    Services.prefs.setBoolPref("media.getusermedia.screensharing.allow_on_old_platforms", true);
     Services.prefs.setCharPref("media.getusermedia.screensharing.allowed_domains",
                                "test1.example.com");
     Services.prefs.setBoolPref("extensions.install.requireBuiltInCerts", false);
     Services.prefs.setBoolPref("signon.rememberSignons", true);
   },
 
   configurations: {
     shareDevices: {

--- a/dom/media/MediaManager.cpp
+++ b/dom/media/MediaManager.cpp
@@ -2110,29 +2110,21 @@ if (privileged) {
           nsPIDOMWindowOuter* outer = aWindow->GetOuterWindow();
           vc.mBrowserWindow.Construct(outer->WindowID());
         }
         MOZ_FALLTHROUGH;
       case MediaSourceEnum::Screen:
       case MediaSourceEnum::Application:
       case MediaSourceEnum::Window:
         // Deny screensharing request if support is disabled, or
-        // the requesting document is not from a host on the whitelist, or
-        // we're on WinXP until proved that it works
+        // the requesting document is not from a host on the whitelist.
         if (!Preferences::GetBool(((videoType == MediaSourceEnum::Browser)?
                                    "media.getusermedia.browser.enabled" :
                                    "media.getusermedia.screensharing.enabled"),
                                   false) ||
-#if defined(XP_WIN)
-            (
-              // Allow tab sharing for all platforms including XP
-              (videoType != MediaSourceEnum::Browser) &&
-              !Preferences::GetBool("media.getusermedia.screensharing.allow_on_old_platforms",
-                                    false) && !IsVistaOrLater()) ||
-#endif
             (!privileged && !HostIsHttps(*docURI))) {
           RefPtr<MediaStreamError> error =
               new MediaStreamError(aWindow,
                                    NS_LITERAL_STRING("NotAllowedError"));
           onFailure->OnError(error);
           return NS_OK;
         }
         break;

--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -542,18 +542,16 @@ pref("media.getusermedia.screensharing.e
 #endif
 
 #ifdef RELEASE_OR_BETA
 pref("media.getusermedia.screensharing.allowed_domains", "webex.com,*.webex.com,ciscospark.com,*.ciscospark.com,projectsquared.com,*.projectsquared.com,*.room.co,room.co,beta.talky.io,talky.io,*.clearslide.com,appear.in,*.appear.in,tokbox.com,*.tokbox.com,*.sso.francetelecom.fr,*.si.francetelecom.fr,*.sso.infra.ftgroup,*.multimedia-conference.orange-business.com,*.espacecollaboration.orange-business.com,free.gotomeeting.com,g2m.me,*.g2m.me,*.mypurecloud.com,*.mypurecloud.com.au,spreed.me,*.spreed.me,*.spreed.com,air.mozilla.org,*.circuit.com,*.yourcircuit.com,circuit.siemens.com,yourcircuit.siemens.com,circuitsandbox.net,*.unify.com,tandi.circuitsandbox.net,*.ericsson.net,*.cct.ericsson.net,*.opentok.com,*.conf.meetecho.com,meet.jit.si,*.meet.jit.si,web.stage.speakeasyapp.net,web.speakeasyapp.net,*.hipchat.me,*.beta-wspbx.com,*.wspbx.com,*.unifiedcloudit.com,*.smartboxuc.com,*.smartbox-uc.com,*.panterranetworks.com,pexipdemo.com,*.pexipdemo.com,pex.me,*.pex.me,*.rd.pexip.com,1click.io,*.1click.io,*.fuze.com,*.fuzemeeting.com,*.thinkingphones.com,gotomeeting.com,*.gotomeeting.com,gotowebinar.com,*.gotowebinar.com,gototraining.com,*.gototraining.com,citrix.com,*.citrix.com,expertcity.com,*.expertcity.com,citrixonline.com,*.citrixonline.com,g2m.me,*.g2m.me,gotomeet.me,*.gotomeet.me,gotomeet.at,*.gotomeet.at,miriadaxdes.miriadax.net,certificacion.miriadax.net,miriadax.net,*.wire.com,sylaps.com,*.sylaps.com,bluejeans.com,*.bluejeans.com,*.a.bluejeans.com,*.bbcollab.com");
 #else
  // includes Mozilla's test domain: mozilla.github.io (not intended for release)
 pref("media.getusermedia.screensharing.allowed_domains", "mozilla.github.io,webex.com,*.webex.com,ciscospark.com,*.ciscospark.com,projectsquared.com,*.projectsquared.com,*.room.co,room.co,beta.talky.io,talky.io,*.clearslide.com,appear.in,*.appear.in,tokbox.com,*.tokbox.com,*.sso.francetelecom.fr,*.si.francetelecom.fr,*.sso.infra.ftgroup,*.multimedia-conference.orange-business.com,*.espacecollaboration.orange-business.com,free.gotomeeting.com,g2m.me,*.g2m.me,*.mypurecloud.com,*.mypurecloud.com.au,spreed.me,*.spreed.me,*.spreed.com,air.mozilla.org,*.circuit.com,*.yourcircuit.com,circuit.siemens.com,yourcircuit.siemens.com,circuitsandbox.net,*.unify.com,tandi.circuitsandbox.net,*.ericsson.net,*.cct.ericsson.net,*.opentok.com,*.conf.meetecho.com,meet.jit.si,*.meet.jit.si,web.stage.speakeasyapp.net,web.speakeasyapp.net,*.hipchat.me,*.beta-wspbx.com,*.wspbx.com,*.unifiedcloudit.com,*.smartboxuc.com,*.smartbox-uc.com,*.panterranetworks.com,pexipdemo.com,*.pexipdemo.com,pex.me,*.pex.me,*.rd.pexip.com,1click.io,*.1click.io,*.fuze.com,*.fuzemeeting.com,*.thinkingphones.com,gotomeeting.com,*.gotomeeting.com,gotowebinar.com,*.gotowebinar.com,gototraining.com,*.gototraining.com,citrix.com,*.citrix.com,expertcity.com,*.expertcity.com,citrixonline.com,*.citrixonline.com,g2m.me,*.g2m.me,gotomeet.me,*.gotomeet.me,gotomeet.at,*.gotomeet.at,miriadaxdes.miriadax.net,certificacion.miriadax.net,miriadax.net,*.wire.com,sylaps.com,*.sylaps.com,bluejeans.com,*.bluejeans.com,*.a.bluejeans.com,*.bbcollab.com");
 #endif
-// OS/X 10.6 and XP have screen/window sharing off by default due to various issues - Caveat emptor
-pref("media.getusermedia.screensharing.allow_on_old_platforms", false);
 
 pref("media.getusermedia.audiocapture.enabled", false);
 
 // TextTrack WebVTT Region extension support.
 pref("media.webvtt.regions.enabled", false);
 
 // AudioTrack and VideoTrack support
 pref("media.track.enabled", false);