Bug 18821: Disable libmdns for Android and Desktop

There should be no need to remove the OS X support introduced in
https://bugzilla.mozilla.org/show_bug.cgi?id=1225726 as enabling this
is governed by a preference (which is actually set to `false`). However,
we remove it at build time as well (defense in depth).

This is basically a backout of the relevant passages of
https://hg.mozilla.org/mozilla-central/rev/6bfb430de85d,
https://hg.mozilla.org/mozilla-central/rev/609b337bf7ab and
https://hg.mozilla.org/mozilla-central/rev/8e092ec5fbbd.

Fixed bug 21861 (Disable additional mDNS code to avoid proxy bypasses)
as well.

dom/presentation/provider/components.conf

@@ -6,9 +6,6 @@
 
 categories = {}
 
-if buildconfig.substs['MOZ_WIDGET_TOOLKIT'] in ('cocoa', 'android'):
-    categories["presentation-device-provider"] = "MulticastDNSDeviceProvider"
-
 Classes = [
     {
         'cid': '{f4079b8b-ede5-4b90-a112-5b415a931deb}',
@@ -16,11 +13,4 @@ Classes = [
         'jsm': 'resource://gre/modules/PresentationControlService.jsm',
         'constructor': 'PresentationControlService',
     },
-    {
-        'cid': '{814f947a-52f7-41c9-94a1-3684797284ac}',
-        'contract_ids': ['@mozilla.org/presentation-device/multicastdns-provider;1'],
-        'type': 'mozilla::dom::presentation::MulticastDNSDeviceProvider',
-        'headers': ['/dom/presentation/provider/MulticastDNSDeviceProvider.h'],
-        'categories': categories,
-    },
 ]

dom/presentation/provider/moz.build

@@ -10,7 +10,6 @@ EXTRA_JS_MODULES += [
 
 UNIFIED_SOURCES += [
     'DeviceProviderHelpers.cpp',
-    'MulticastDNSDeviceProvider.cpp',
 ]
 
 XPCOM_MANIFESTS += [

netwerk/dns/mdns/libmdns/components.conf

@@ -5,20 +5,5 @@
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 Classes = [
-    {
-        'cid': '{14a50f2b-7ff6-48a5-88e3-615fd111f5d3}',
-        'contract_ids': ['@mozilla.org/toolkit/components/mdnsresponder/dns-info;1'],
-        'type': 'mozilla::net::nsDNSServiceInfo',
-        'headers': ['/netwerk/dns/mdns/libmdns/nsDNSServiceInfo.h'],
-    },
 ]
 
-if buildconfig.substs['MOZ_WIDGET_TOOLKIT'] != 'cocoa':
-    Classes += [
-        {
-            'cid': '{f9346d98-f27a-4e89-b744-493843416480}',
-            'contract_ids': ['@mozilla.org/toolkit/components/mdnsresponder/dns-sd;1'],
-            'jsm': 'resource://gre/modules/DNSServiceDiscovery.jsm',
-            'constructor': 'nsDNSServiceDiscovery',
-        },
-    ]

netwerk/dns/mdns/libmdns/moz.build

@@ -4,34 +4,6 @@
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
-if CONFIG['MOZ_WIDGET_TOOLKIT'] == 'cocoa':
-    UNIFIED_SOURCES += [
-        'MDNSResponderOperator.cpp',
-        'MDNSResponderReply.cpp',
-        'nsDNSServiceDiscovery.cpp',
-    ]
-
-    LOCAL_INCLUDES += [
-      '/netwerk/base',
-    ]
-
-else:
-    EXTRA_JS_MODULES += [
-        'DNSServiceDiscovery.jsm',
-        'fallback/DataReader.jsm',
-        'fallback/DataWriter.jsm',
-        'fallback/DNSPacket.jsm',
-        'fallback/DNSRecord.jsm',
-        'fallback/DNSResourceRecord.jsm',
-        'fallback/DNSTypes.jsm',
-        'fallback/MulticastDNS.jsm',
-    ]
-
-    if CONFIG['MOZ_WIDGET_TOOLKIT'] == 'android':
-        EXTRA_JS_MODULES += [
-            'MulticastDNSAndroid.jsm',
-        ]
-
 UNIFIED_SOURCES += [
     'nsDNSServiceInfo.cpp',
 ]