--- a/b2g/installer/package-manifest.in
+++ b/b2g/installer/package-manifest.in
@@ -540,16 +540,19 @@
 @BINPATH@/components/ActivityWrapper.js
 @BINPATH@/components/ActivityMessageConfigurator.js
 
 @BINPATH@/components/TCPSocket.js
 @BINPATH@/components/TCPServerSocket.js
 @BINPATH@/components/TCPSocketParentIntermediary.js
 @BINPATH@/components/TCPSocket.manifest
 
+@BINPATH@/components/AppProtocolHandler.js
+@BINPATH@/components/AppProtocolHandler.manifest
+
 @BINPATH@/components/Payment.js
 @BINPATH@/components/PaymentFlowInfo.js
 @BINPATH@/components/PaymentRequestInfo.js
 @BINPATH@/components/Payment.manifest
 
 ; InputMethod API
 @BINPATH@/components/MozKeyboard.js
 @BINPATH@/components/InputMethod.manifest

--- a/browser/installer/package-manifest.in
+++ b/browser/installer/package-manifest.in
@@ -516,16 +516,19 @@
 @BINPATH@/components/Push.js
 @BINPATH@/components/Push.manifest
 @BINPATH@/components/PushServiceLauncher.js
 @BINPATH@/components/TCPSocket.js
 @BINPATH@/components/TCPServerSocket.js
 @BINPATH@/components/TCPSocketParentIntermediary.js
 @BINPATH@/components/TCPSocket.manifest
 
+@BINPATH@/components/AppProtocolHandler.js
+@BINPATH@/components/AppProtocolHandler.manifest
+
 @BINPATH@/components/Payment.js
 @BINPATH@/components/PaymentFlowInfo.js
 @BINPATH@/components/PaymentRequestInfo.js
 @BINPATH@/components/Payment.manifest
 
 #ifdef MOZ_WEBRTC
 @BINPATH@/components/PeerConnection.js
 @BINPATH@/components/PeerConnection.manifest

--- a/configure.in
+++ b/configure.in
@@ -3981,17 +3981,17 @@ MOZ_UNIVERSALCHARDET=1
 MOZ_URL_CLASSIFIER=
 MOZ_XUL=1
 MOZ_ZIPWRITER=1
 NS_PRINTING=1
 MOZ_PDF_PRINTING=
 MOZ_DISABLE_CRYPTOLEGACY=
 NSS_DISABLE_DBM=
 NECKO_COOKIES=1
-NECKO_PROTOCOLS_DEFAULT="about app data file ftp http res viewsource websocket wyciwyg device"
+NECKO_PROTOCOLS_DEFAULT="about data file ftp http res viewsource websocket wyciwyg device"
 USE_ARM_KUSER=
 BUILD_CTYPES=1
 MOZ_USE_NATIVE_POPUP_WINDOWS=
 MOZ_ANDROID_HISTORY=
 MOZ_WEBSMS_BACKEND=
 MOZ_ANDROID_BEAM=
 ACCESSIBILITY=1
 MOZ_TIME_MANAGER=

deleted file mode 100644
--- a/dom/webidl/AppInfo.webidl
+++ /dev/null
@@ -1,12 +0,0 @@
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * 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/. */
-
-/**
-  * This dictionnary holds the parameters supporting the app:// protocol.
-  */
-dictionary AppInfo
-{
-  DOMString path = "";
-  boolean   isCoreApp = false;
-};

--- a/dom/webidl/DummyBinding.webidl
+++ b/dom/webidl/DummyBinding.webidl
@@ -23,14 +23,13 @@ interface DummyInterface : EventTarget {
   void MmsParameters(optional MmsParameters arg);
   void MmsAttachment(optional MmsAttachment arg);
   void AsyncScrollEventDetail(optional AsyncScrollEventDetail arg);
   void OpenWindowEventDetail(optional OpenWindowEventDetail arg);
   void DOMWindowResizeEventDetail(optional DOMWindowResizeEventDetail arg);
   void WifiOptions(optional WifiCommandOptions arg1,
                    optional WifiResultOptions arg2);
   void AppNotificationServiceOptions(optional AppNotificationServiceOptions arg);
-  void AppInfo(optional AppInfo arg1);
 };
 
 interface DummyInterfaceWorkers {
   BlobPropertyBag blobBag();
 };

--- a/dom/webidl/moz.build
+++ b/dom/webidl/moz.build
@@ -14,17 +14,16 @@ PREPROCESSED_WEBIDL_FILES = [
     'Crypto.webidl',
     'Navigator.webidl',
 ]
 
 WEBIDL_FILES = [
     'AbstractWorker.webidl',
     'AnalyserNode.webidl',
     'AnimationEvent.webidl',
-    'AppInfo.webidl',
     'AppNotificationServiceOptions.webidl',
     'ArchiveReader.webidl',
     'ArchiveRequest.webidl',
     'Attr.webidl',
     'AudioBuffer.webidl',
     'AudioBufferSourceNode.webidl',
     'AudioContext.webidl',
     'AudioDestinationNode.webidl',

--- a/mobile/android/installer/package-manifest.in
+++ b/mobile/android/installer/package-manifest.in
@@ -382,16 +382,18 @@
 @BINPATH@/components/nsPrompter.manifest
 @BINPATH@/components/nsPrompter.js
 @BINPATH@/components/TelemetryPing.js
 @BINPATH@/components/TelemetryPing.manifest
 @BINPATH@/components/Webapps.js
 @BINPATH@/components/Webapps.manifest
 @BINPATH@/components/AppsService.js
 @BINPATH@/components/AppsService.manifest
+@BINPATH@/components/AppProtocolHandler.js
+@BINPATH@/components/AppProtocolHandler.manifest
 
 @BINPATH@/components/Push.js
 @BINPATH@/components/Push.manifest
 
 @BINPATH@/components/SystemMessageInternal.js
 @BINPATH@/components/SystemMessageManager.js
 @BINPATH@/components/SystemMessageManager.manifest
 

--- a/netwerk/build/Makefile.in
+++ b/netwerk/build/Makefile.in
@@ -64,17 +64,16 @@ LOCAL_INCLUDES = \
   -I$(srcdir)/../base/src \
   -I$(srcdir)/../dns \
   -I$(srcdir)/../socket \
   -I$(srcdir)/../streamconv/src \
   -I$(srcdir)/../streamconv/converters \
   -I$(srcdir)/../mime \
   -I$(srcdir)/../cache \
   -I$(srcdir)/../protocol/about \
-  -I$(srcdir)/../protocol/app \
   -I../dns \
   $(foreach d,$(filter-out about,$(NECKO_PROTOCOLS)), \
     -I$(srcdir)/../protocol/$(d)) \
   $(NULL)
 
 ifeq ($(OS_ARCH),WINNT)
     LOCAL_INCLUDES += -I$(srcdir)/../system/win32
 endif

--- a/netwerk/build/nsNetCID.h
+++ b/netwerk/build/nsNetCID.h
@@ -598,28 +598,16 @@
 { /* fbc81170-1f69-11d3-9344-00104ba0fd40 */         \
     0xfbc81170,                                      \
     0x1f69,                                          \
     0x11d3,                                          \
     {0x93, 0x44, 0x00, 0x10, 0x4b, 0xa0, 0xfd, 0x40} \
 }
 
 /******************************************************************************
- * netwerk/protocol/app/ classes
- */
-
-#define NS_APPPROTOCOLHANDLER_CID                    \
-{ /* {B6ED3030-9999-11d3-A178-0050041CAF44} */       \
-    0xb6ed3030,                                      \
-    0x9999,                                          \
-    0x11d3,                                          \
-    {0xa1, 0x78, 0x00, 0x50, 0x04, 0x1c, 0xaf, 0x44} \
-}
-
-/******************************************************************************
  * netwerk/protocol/data/ classes
  */
 
 #define NS_DATAPROTOCOLHANDLER_CID                   \
 { /* {B6ED3030-6183-11d3-A178-0050041CAF44} */       \
     0xb6ed3030,                                      \
     0x6183,                                          \
     0x11d3,                                          \

--- a/netwerk/build/nsNetModule.cpp
+++ b/netwerk/build/nsNetModule.cpp
@@ -238,17 +238,16 @@ NS_GENERIC_FACTORY_CONSTRUCTOR(nsHttpDig
 #endif // !NECKO_PROTOCOL_http
 
 #include "mozilla/net/Dashboard.h"
 namespace mozilla {
 namespace net {
   NS_GENERIC_FACTORY_CONSTRUCTOR(Dashboard)
 }
 }
-#include "AppProtocolHandler.h"
 
 #ifdef NECKO_PROTOCOL_res
 // resource
 #include "nsResProtocolHandler.h"
 NS_GENERIC_FACTORY_CONSTRUCTOR_INIT(nsResProtocolHandler, Init)
 NS_GENERIC_FACTORY_CONSTRUCTOR(nsResURL)
 #endif
 
@@ -768,17 +767,16 @@ NS_DEFINE_NAMED_CID(NS_ABOUT_CACHE_ENTRY
 #endif
 NS_DEFINE_NAMED_CID(NS_SOCKSSOCKETPROVIDER_CID);
 NS_DEFINE_NAMED_CID(NS_SOCKS4SOCKETPROVIDER_CID);
 NS_DEFINE_NAMED_CID(NS_UDPSOCKETPROVIDER_CID);
 NS_DEFINE_NAMED_CID(NS_CACHESERVICE_CID);
 NS_DEFINE_NAMED_CID(NS_APPLICATIONCACHESERVICE_CID);
 NS_DEFINE_NAMED_CID(NS_APPLICATIONCACHENAMESPACE_CID);
 NS_DEFINE_NAMED_CID(NS_APPLICATIONCACHE_CID);
-NS_DEFINE_NAMED_CID(NS_APPPROTOCOLHANDLER_CID);
 #ifdef NECKO_COOKIES
 NS_DEFINE_NAMED_CID(NS_COOKIEMANAGER_CID);
 NS_DEFINE_NAMED_CID(NS_COOKIESERVICE_CID);
 #endif
 #ifdef NECKO_WIFI
 NS_DEFINE_NAMED_CID(NS_WIFI_MONITOR_COMPONENT_CID);
 #endif
 #ifdef NECKO_PROTOCOL_data
@@ -907,17 +905,16 @@ static const mozilla::Module::CIDEntry k
 #endif
     { &kNS_SOCKSSOCKETPROVIDER_CID, false, nullptr, nsSOCKSSocketProvider::CreateV5 },
     { &kNS_SOCKS4SOCKETPROVIDER_CID, false, nullptr, nsSOCKSSocketProvider::CreateV4 },
     { &kNS_UDPSOCKETPROVIDER_CID, false, nullptr, nsUDPSocketProviderConstructor },
     { &kNS_CACHESERVICE_CID, false, nullptr, nsCacheService::Create },
     { &kNS_APPLICATIONCACHESERVICE_CID, false, nullptr, nsApplicationCacheServiceConstructor },
     { &kNS_APPLICATIONCACHENAMESPACE_CID, false, nullptr, nsApplicationCacheNamespaceConstructor },
     { &kNS_APPLICATIONCACHE_CID, false, nullptr, nsApplicationCacheConstructor },
-    { &kNS_APPPROTOCOLHANDLER_CID, false, nullptr, AppProtocolHandler::Create },
 #ifdef NECKO_COOKIES
     { &kNS_COOKIEMANAGER_CID, false, nullptr, nsICookieServiceConstructor },
     { &kNS_COOKIESERVICE_CID, false, nullptr, nsICookieServiceConstructor },
 #endif
 #ifdef NECKO_WIFI
     { &kNS_WIFI_MONITOR_COMPONENT_CID, false, nullptr, nsWifiMonitorConstructor },
 #endif
 #ifdef NECKO_PROTOCOL_data
@@ -1053,17 +1050,16 @@ static const mozilla::Module::ContractID
 #endif
     { NS_NETWORK_SOCKET_CONTRACTID_PREFIX "socks", &kNS_SOCKSSOCKETPROVIDER_CID },
     { NS_NETWORK_SOCKET_CONTRACTID_PREFIX "socks4", &kNS_SOCKS4SOCKETPROVIDER_CID },
     { NS_NETWORK_SOCKET_CONTRACTID_PREFIX "udp", &kNS_UDPSOCKETPROVIDER_CID },
     { NS_CACHESERVICE_CONTRACTID, &kNS_CACHESERVICE_CID },
     { NS_APPLICATIONCACHESERVICE_CONTRACTID, &kNS_APPLICATIONCACHESERVICE_CID },
     { NS_APPLICATIONCACHENAMESPACE_CONTRACTID, &kNS_APPLICATIONCACHENAMESPACE_CID },
     { NS_APPLICATIONCACHE_CONTRACTID, &kNS_APPLICATIONCACHE_CID },
-    { NS_NETWORK_PROTOCOL_CONTRACTID_PREFIX "app", &kNS_APPPROTOCOLHANDLER_CID },
 #ifdef NECKO_COOKIES
     { NS_COOKIEMANAGER_CONTRACTID, &kNS_COOKIEMANAGER_CID },
     { NS_COOKIESERVICE_CONTRACTID, &kNS_COOKIESERVICE_CID },
 #endif
 #ifdef NECKO_WIFI
     { NS_WIFI_MONITOR_CONTRACTID, &kNS_WIFI_MONITOR_COMPONENT_CID },
 #endif
 #ifdef NECKO_PROTOCOL_data

deleted file mode 100644
--- a/netwerk/protocol/app/AppProtocolHandler.cpp
+++ /dev/null
@@ -1,424 +0,0 @@
-/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
-/* vim:set expandtab ts=4 sw=4 sts=4 cin: */
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * 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/. */
-
-#include "AppProtocolHandler.h"
-#include "nsBaseChannel.h"
-#include "nsJARChannel.h"
-#include "nsNetCID.h"
-#include "nsIAppsService.h"
-#include "nsCxPusher.h"
-#include "nsXULAppAPI.h"
-
-/**
-  * This dummy channel implementation only provides enough functionality
-  * to return a fake 404 error when the caller asks for an app:// URL
-  * containing an unknown appId.
-  */
-class DummyChannel : public nsIJARChannel
-                          , nsRunnable
-{
-public:
-  NS_DECL_ISUPPORTS
-  NS_DECL_NSIREQUEST
-  NS_DECL_NSICHANNEL
-  NS_DECL_NSIJARCHANNEL
-
-  DummyChannel();
-
-  NS_IMETHODIMP Run();
-
-private:
-  bool                        mPending;
-  uint32_t                    mSuspendCount;
-  nsCOMPtr<nsISupports>       mListenerContext;
-  nsCOMPtr<nsIStreamListener> mListener;
-  nsCOMPtr<nsILoadGroup>      mLoadGroup;
-  nsLoadFlags                 mLoadFlags;
-};
-
-NS_IMPL_ISUPPORTS3(DummyChannel, nsIRequest, nsIChannel, nsIJARChannel)
-
-DummyChannel::DummyChannel() : mPending(false)
-                             , mSuspendCount(0)
-                             , mLoadFlags(LOAD_NORMAL)
-{
-}
-
-NS_IMETHODIMP DummyChannel::GetName(nsACString &result)
-{
-  result = "dummy_app_channel";
-  return NS_OK;
-}
-
-NS_IMETHODIMP DummyChannel::GetStatus(nsresult *aStatus)
-{
-  *aStatus = NS_ERROR_FILE_NOT_FOUND;
-  return NS_OK;
-}
-
-NS_IMETHODIMP DummyChannel::IsPending(bool *aResult)
-{
-  *aResult = mPending;
-  return NS_OK;
-}
-
-NS_IMETHODIMP DummyChannel::Suspend()
-{
-  mSuspendCount++;
-  return NS_OK;
-}
-
-NS_IMETHODIMP DummyChannel::Resume()
-{
-  if (mSuspendCount <= 0) {
-    return NS_ERROR_UNEXPECTED;
-  }
-
-  if (--mSuspendCount == 0) {
-    NS_DispatchToMainThread(this, NS_DISPATCH_NORMAL);
-  }
-  return NS_OK;
-}
-
-NS_IMETHODIMP DummyChannel::Open(nsIInputStream**)
-{
-  return NS_ERROR_NOT_IMPLEMENTED;
-}
-
-NS_IMETHODIMP DummyChannel::AsyncOpen(nsIStreamListener* aListener, nsISupports* aContext)
-{
-  mListener = aListener;
-  mListenerContext = aContext;
-  mPending = true;
-
-  if (mLoadGroup) {
-    mLoadGroup->AddRequest(this, aContext);
-  }
-
-  if (mSuspendCount == 0) {
-    NS_DispatchToMainThread(this, NS_DISPATCH_NORMAL);
-  }
-
-  return NS_OK;
-}
-
-// nsIJarChannel, needed for XHR to turn NS_ERROR_FILE_NOT_FOUND into
-// a 404 error.
-NS_IMETHODIMP DummyChannel::GetIsUnsafe(bool *aResult)
-{
-  *aResult = false;
-  return NS_OK;
-}
-
-NS_IMETHODIMP DummyChannel::SetAppURI(nsIURI *aURI)
-{
-  return NS_ERROR_NOT_IMPLEMENTED;
-}
-
-NS_IMETHODIMP DummyChannel::Run()
-{
-  nsresult rv = mListener->OnStartRequest(this, mListenerContext);
-  NS_ENSURE_SUCCESS(rv, rv);
-  mPending = false;
-  rv = mListener->OnStopRequest(this, mListenerContext, NS_ERROR_FILE_NOT_FOUND);
-  NS_ENSURE_SUCCESS(rv, rv);
-  if (mLoadGroup) {
-    mLoadGroup->RemoveRequest(this, mListenerContext, NS_ERROR_FILE_NOT_FOUND);
-  }
-
-  mListener = nullptr;
-  mListenerContext = nullptr;
-  rv = SetNotificationCallbacks(nullptr);
-  NS_ENSURE_SUCCESS(rv, rv);
-
-  return NS_OK;
-}
-
-NS_IMETHODIMP DummyChannel::Cancel(nsresult)
-{
-  return NS_ERROR_NOT_IMPLEMENTED;
-}
-
-NS_IMETHODIMP DummyChannel::GetLoadGroup(nsILoadGroup* *aLoadGroup)
-{
-  *aLoadGroup = mLoadGroup;
-  NS_IF_ADDREF(*aLoadGroup);
-  return NS_OK;
-}
-
-NS_IMETHODIMP DummyChannel::SetLoadGroup(nsILoadGroup* aLoadGroup)
-{
-  mLoadGroup = aLoadGroup;
-  return NS_OK;
-}
-
-NS_IMETHODIMP DummyChannel::GetLoadFlags(nsLoadFlags *aLoadFlags)
-{
-  *aLoadFlags = mLoadFlags;
-  return NS_OK;
-}
-
-NS_IMETHODIMP DummyChannel::SetLoadFlags(nsLoadFlags aLoadFlags)
-{
-  mLoadFlags = aLoadFlags;
-  return NS_OK;
-}
-
-NS_IMETHODIMP DummyChannel::GetOriginalURI(nsIURI**)
-{
-  return NS_ERROR_NOT_IMPLEMENTED;
-}
-
-NS_IMETHODIMP DummyChannel::SetOriginalURI(nsIURI*)
-{
-  return NS_ERROR_NOT_IMPLEMENTED;
-}
-
-NS_IMETHODIMP DummyChannel::GetOwner(nsISupports**)
-{
-  return NS_ERROR_NOT_IMPLEMENTED;
-}
-
-NS_IMETHODIMP DummyChannel::SetOwner(nsISupports*)
-{
-  return NS_ERROR_NOT_IMPLEMENTED;
-}
-
-NS_IMETHODIMP DummyChannel::GetNotificationCallbacks(nsIInterfaceRequestor**)
-{
-  return NS_ERROR_NOT_IMPLEMENTED;
-}
-
-NS_IMETHODIMP DummyChannel::SetNotificationCallbacks(nsIInterfaceRequestor*)
-{
-  return NS_ERROR_NOT_IMPLEMENTED;
-}
-
-NS_IMETHODIMP DummyChannel::GetSecurityInfo(nsISupports**)
-{
-  return NS_ERROR_NOT_IMPLEMENTED;
-}
-
-NS_IMETHODIMP DummyChannel::GetContentType(nsACString&)
-{
-  return NS_ERROR_NOT_IMPLEMENTED;
-}
-
-NS_IMETHODIMP DummyChannel::SetContentType(const nsACString&)
-{
-  return NS_ERROR_NOT_IMPLEMENTED;
-}
-
-NS_IMETHODIMP DummyChannel::GetContentCharset(nsACString&)
-{
-  return NS_ERROR_NOT_IMPLEMENTED;
-}
-
-NS_IMETHODIMP DummyChannel::SetContentCharset(const nsACString&)
-{
-  return NS_ERROR_NOT_IMPLEMENTED;
-}
-
-NS_IMETHODIMP DummyChannel::GetContentLength(int64_t*)
-{
-  return NS_ERROR_NOT_IMPLEMENTED;
-}
-
-NS_IMETHODIMP DummyChannel::SetContentLength(int64_t)
-{
-  return NS_ERROR_NOT_IMPLEMENTED;
-}
-
-NS_IMETHODIMP DummyChannel::GetContentDisposition(uint32_t*)
-{
-  return NS_ERROR_NOT_IMPLEMENTED;
-}
-
-NS_IMETHODIMP DummyChannel::SetContentDisposition(uint32_t)
-{
-  return NS_ERROR_NOT_IMPLEMENTED;
-}
-
-NS_IMETHODIMP DummyChannel::GetURI(nsIURI**)
-{
-  return NS_ERROR_NOT_IMPLEMENTED;
-}
-
-NS_IMETHODIMP DummyChannel::GetContentDispositionFilename(nsAString&)
-{
-  return NS_ERROR_NOT_IMPLEMENTED;
-}
-
-NS_IMETHODIMP DummyChannel::SetContentDispositionFilename(nsAString const &)
-{
-  return NS_ERROR_NOT_IMPLEMENTED;
-}
-
-NS_IMETHODIMP DummyChannel::GetContentDispositionHeader(nsACString&)
-{
-  return NS_ERROR_NOT_IMPLEMENTED;
-}
-
-/**
-  * app:// protocol implementation.
-  */
-
-AppProtocolHandler::AppProtocolHandler() {
-}
-
-AppProtocolHandler::~AppProtocolHandler() {
-  mAppInfoCache.Clear();
-}
-
-NS_IMPL_ISUPPORTS1(AppProtocolHandler, nsIProtocolHandler)
-
-/* static */
-nsresult
-AppProtocolHandler::Create(nsISupports* aOuter,
-                           const nsIID& aIID,
-                           void* *aResult)
-{
-  AppProtocolHandler* ph = new AppProtocolHandler();
-  if (ph == nullptr) {
-    return NS_ERROR_OUT_OF_MEMORY;
-  }
-  NS_ADDREF(ph);
-  nsresult rv = ph->QueryInterface(aIID, aResult);
-  NS_RELEASE(ph);
-  return rv;
-}
-
-NS_IMETHODIMP
-AppProtocolHandler::GetScheme(nsACString &aResult)
-{
-  aResult.AssignLiteral("app");
-  return NS_OK;
-}
-
-NS_IMETHODIMP
-AppProtocolHandler::GetDefaultPort(int32_t *aResult)
-{
-  // No ports for the app protocol.
-  *aResult = -1;
-  return NS_OK;
-}
-
-NS_IMETHODIMP
-AppProtocolHandler::GetProtocolFlags(uint32_t *aResult)
-{
-  *aResult = URI_NOAUTH |
-             URI_DANGEROUS_TO_LOAD |
-             URI_CROSS_ORIGIN_NEEDS_WEBAPPS_PERM;
-  return NS_OK;
-}
-
-NS_IMETHODIMP
-AppProtocolHandler::NewURI(const nsACString &aSpec,
-                           const char *aCharset, // ignore charset info
-                           nsIURI *aBaseURI,
-                           nsIURI **result)
-{
-  nsresult rv;
-  nsCOMPtr<nsIStandardURL> surl(do_CreateInstance(NS_STANDARDURL_CONTRACTID, &rv));
-  NS_ENSURE_SUCCESS(rv, rv);
-
-  rv = surl->Init(nsIStandardURL::URLTYPE_STANDARD, -1, aSpec, aCharset, aBaseURI);
-  NS_ENSURE_SUCCESS(rv, rv);
-
-  nsCOMPtr<nsIURL> url(do_QueryInterface(surl, &rv));
-  NS_ENSURE_SUCCESS(rv, rv);
-
-  surl->SetMutable(false);
-  NS_ADDREF(*result = url);
-  return NS_OK;
-}
-
-// We map app://ABCDEF/path/to/file.ext to
-// jar:file:///path/to/profile/webapps/ABCDEF/application.zip!/path/to/file.ext
-NS_IMETHODIMP
-AppProtocolHandler::NewChannel(nsIURI* aUri, nsIChannel* *aResult)
-{
-  NS_ENSURE_ARG_POINTER(aUri);
-  nsJARChannel* channel = new nsJARChannel();
-  if (!channel) {
-    return NS_ERROR_OUT_OF_MEMORY;
-  }
-
-  nsAutoCString host;
-  nsresult rv = aUri->GetHost(host);
-  NS_ENSURE_SUCCESS(rv, rv);
-
-  nsAutoCString fileSpec;
-  nsCOMPtr<nsIURL> url = do_QueryInterface(aUri);
-  rv = url->GetFilePath(fileSpec);
-  NS_ENSURE_SUCCESS(rv, rv);
-
-  mozilla::dom::AppInfo appInfo;
-
-  if (!mAppInfoCache.Get(host, &appInfo)) {
-    nsCOMPtr<nsIAppsService> appsService = do_GetService(APPS_SERVICE_CONTRACTID);
-    if (!appsService) {
-      return NS_ERROR_FAILURE;
-    }
-
-    JS::Value jsInfo;
-    rv = appsService->GetAppInfo(NS_ConvertUTF8toUTF16(host), &jsInfo);
-    if (NS_FAILED(rv)) {
-      // Return a DummyChannel.
-      delete channel;
-      NS_IF_ADDREF(*aResult = new DummyChannel());
-      return NS_OK;
-    }
-
-    mozilla::AutoSafeJSContext cx;
-    if (!appInfo.Init(cx, JS::Handle<JS::Value>::fromMarkedLocation(&jsInfo)) ||
-        appInfo.mPath.IsEmpty()) {
-      printf_stderr("!! No appInfo for %s\n", host.get());
-      // Return a DummyChannel.
-      delete channel;
-      NS_IF_ADDREF(*aResult = new DummyChannel());
-      return NS_OK;
-    }
-
-    mAppInfoCache.Put(host, appInfo);
-  }
-
-  bool noRemote = (appInfo.mIsCoreApp ||
-                   XRE_GetProcessType() == GeckoProcessType_Default);
-
-  // In-parent and CoreApps can directly access files, so use jar:file://
-  nsAutoCString jarSpec(noRemote ? "jar:file://"
-                                 : "jar:remoteopenfile://");
-  jarSpec += NS_ConvertUTF16toUTF8(appInfo.mPath) +
-             NS_LITERAL_CSTRING("/application.zip!") +
-             fileSpec;
-
-  nsCOMPtr<nsIURI> jarURI;
-  rv = NS_NewURI(getter_AddRefs(jarURI),
-                 jarSpec, nullptr, nullptr);
-  NS_ENSURE_SUCCESS(rv, rv);
-
-  rv = channel->Init(jarURI);
-  NS_ENSURE_SUCCESS(rv, rv);
-
-  rv = channel->SetAppURI(aUri);
-  NS_ENSURE_SUCCESS(rv, rv);
-
-  rv = channel->SetOriginalURI(aUri);
-  NS_ENSURE_SUCCESS(rv, rv);
-
-  NS_ADDREF(*aResult = channel);
-  return NS_OK;
-}
-
-NS_IMETHODIMP
-AppProtocolHandler::AllowPort(int32_t aPort, const char *aScheme, bool *aRetval)
-{
-  // No port allowed for this scheme.
-  *aRetval = false;
-  return NS_OK;
-}
-

deleted file mode 100644
--- a/netwerk/protocol/app/AppProtocolHandler.h
+++ /dev/null
@@ -1,35 +0,0 @@
-/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
-/* vim:set expandtab ts=4 sw=4 sts=4 cin: */
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * 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/. */
-
-#ifndef AppProtocolHandler_
-#define AppProtocolHandler_
-
-#include "nsIProtocolHandler.h"
-#include "nsDataHashtable.h"
-#include "mozilla/dom/AppInfoBinding.h"
-
-class AppProtocolHandler : public nsIProtocolHandler
-{
-public:
-  NS_DECL_ISUPPORTS
-
-  // nsIProtocolHandler methods:
-  NS_DECL_NSIPROTOCOLHANDLER
-
-  // AppProtocolHandler methods:
-  AppProtocolHandler();
-  virtual ~AppProtocolHandler();
-
-  // Define a Create method to be used with a factory:
-  static nsresult Create(nsISupports* aOuter,
-                         const nsIID& aIID,
-                         void* *aResult);
-
-private:
-  nsDataHashtable<nsCStringHashKey, mozilla::dom::AppInfo> mAppInfoCache;
-};
-
-#endif /* AppProtocolHandler_ */

new file mode 100644
--- /dev/null
+++ b/netwerk/protocol/app/AppProtocolHandler.js
@@ -0,0 +1,197 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * 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/. */
+
+"use strict";
+
+const Cc = Components.classes;
+const Ci = Components.interfaces;
+const Cu = Components.utils;
+const Cr = Components.results;
+
+Cu.import("resource://gre/modules/XPCOMUtils.jsm");
+Cu.import("resource://gre/modules/Services.jsm");
+
+XPCOMUtils.defineLazyServiceGetter(this, "appsService",
+                                   "@mozilla.org/AppsService;1",
+                                   "nsIAppsService");
+
+function AppProtocolHandler() {
+  this._appInfo = [];
+  this._runningInParent = Cc["@mozilla.org/xre/runtime;1"]
+                            .getService(Ci.nsIXULRuntime)
+                            .processType == Ci.nsIXULRuntime.PROCESS_TYPE_DEFAULT;
+}
+
+AppProtocolHandler.prototype = {
+  classID: Components.ID("{b7ad6144-d344-4687-b2d0-b6b9dce1f07f}"),
+  QueryInterface: XPCOMUtils.generateQI([Ci.nsIProtocolHandler]),
+
+  scheme: "app",
+  defaultPort: -1,
+  // Don't allow loading from other protocols, and only from app:// if webapps is granted
+  protocolFlags: Ci.nsIProtocolHandler.URI_NOAUTH |
+                 Ci.nsIProtocolHandler.URI_DANGEROUS_TO_LOAD |
+                 Ci.nsIProtocolHandler.URI_CROSS_ORIGIN_NEEDS_WEBAPPS_PERM,
+
+  getAppInfo: function app_phGetAppInfo(aId) {
+
+    if (!this._appInfo[aId]) {
+      this._appInfo[aId] = appsService.getAppInfo(aId);
+    }
+    return this._appInfo[aId];
+  },
+
+  newURI: function app_phNewURI(aSpec, aOriginCharset, aBaseURI) {
+    let uri = Cc["@mozilla.org/network/standard-url;1"]
+              .createInstance(Ci.nsIStandardURL);
+    uri.init(Ci.nsIStandardURL.URLTYPE_STANDARD, -1, aSpec, aOriginCharset,
+             aBaseURI);
+    return uri.QueryInterface(Ci.nsIURI);
+  },
+
+  newChannel: function app_phNewChannel(aURI) {
+    // We map app://ABCDEF/path/to/file.ext to
+    // jar:file:///path/to/profile/webapps/ABCDEF/application.zip!/path/to/file.ext
+    let url = aURI.QueryInterface(Ci.nsIURL);
+    let appId = aURI.host;
+    let fileSpec = url.filePath;
+
+    // Build a jar channel and masquerade as an app:// URI.
+    let appInfo = this.getAppInfo(appId);
+    if (!appInfo) {
+      // That should not happen, so dump() inconditionnally.
+      // We create a dummy channel instead of throwing to let the
+      // downstream user get a 404 error.
+      dump("!! got no appInfo for " + appId + "\n");
+      return new DummyChannel();
+    }
+
+    let uri;
+    if (this._runningInParent || appInfo.isCoreApp) {
+      // In-parent and CoreApps can directly access files, so use jar:file://
+      uri = "jar:file://" + appInfo.path + "/application.zip!" + fileSpec;
+    } else {
+      // non-CoreApps in child need to ask parent for file handle, use jar:ipcfile://
+      uri = "jar:remoteopenfile://" + appInfo.path + "/application.zip!" + fileSpec;
+    }
+    let channel = Services.io.newChannel(uri, null, null);
+    channel.QueryInterface(Ci.nsIJARChannel).setAppURI(aURI);
+    channel.QueryInterface(Ci.nsIChannel).originalURI = aURI;
+
+    return channel;
+  },
+
+  allowPort: function app_phAllowPort(aPort, aScheme) {
+    return false;
+  }
+};
+
+/**
+  * This dummy channel implementation only provides enough functionality
+  * to return a fake 404 error when the caller asks for an app:// URL
+  * containing an unknown appId.
+  */
+function DummyChannel() {
+  this.originalURI = Services.io.newURI("app://unknown/nothing.html", null, null);
+  this.URI = Services.io.newURI("app://unknown/nothing.html", null, null);
+}
+
+DummyChannel.prototype = {
+  QueryInterface: XPCOMUtils.generateQI([Ci.nsIRequest,
+                                         Ci.nsIChannel,
+                                         Ci.nsIJARChannel]),
+
+  // nsIRequest
+  name: "dummy_app_channel",
+
+  isPending: function dc_isPending() {
+    return this._pending;
+  },
+
+  status: Cr.NS_ERROR_FILE_NOT_FOUND,
+
+  cancel: function dc_cancel() {
+  },
+
+  suspend: function dc_suspend() {
+    this._suspendCount++;
+  },
+
+  resume: function dc_resume() {
+    if (this._suspendCount <= 0)
+      throw Cr.NS_ERROR_UNEXPECTED;
+
+    if (--this._suspendCount == 0 && this._pending) {
+      this._dispatch();
+    }
+  },
+
+  loadGroup: null,
+  loadFlags: Ci.nsIRequest.LOAD_NORMAL,
+
+  // nsIChannel
+  owner: null,
+  notificationCallbacks: null,
+  securityInfo: null,
+  contentType: null,
+  contentCharset: null,
+  contentLength: 0,
+  contentDisposition: Ci.nsIChannel.DISPOSITION_INLINE,
+  contentDispositionFilename: "",
+
+  _pending: false,
+  _suspendCount: 0,
+  _listener: null,
+  _context: null,
+
+  open: function dc_open() {
+    return Cr.NS_ERROR_NOT_IMPLEMENTED;
+  },
+
+  _dispatch: function dc_dispatch() {
+    let request = this;
+
+    Services.tm.currentThread.dispatch(
+    {
+      run: function dc_run() {
+        request._listener.onStartRequest(request, request._context);
+        request._listener.onStopRequest(request, request._context,
+                                        Cr.NS_ERROR_FILE_NOT_FOUND);
+        if (request.loadGroup) {
+          request.loadGroup.removeRequest(request, request._context,
+                                          Cr.NS_ERROR_FILE_NOT_FOUND);
+        }
+        request._pending = false;
+        request.notificationCallbacks = null;
+        request._listener = null;
+        request._context = null;
+      }
+    },
+    Ci.nsIThread.DISPATCH_NORMAL);
+  },
+
+  asyncOpen: function dc_asyncopenfunction(aListener, aContext) {
+    if (this.loadGroup) {
+      this.loadGroup.addRequest(this, aContext);
+    }
+
+    this._listener = aListener;
+    this._context = aContext;
+    this._pending = true;
+
+    if (!this._suspended) {
+      this._dispatch();
+    }
+  },
+
+  // nsIJarChannel, needed for XHR to turn NS_ERROR_FILE_NOT_FOUND into
+  // a 404 error.
+  isUnsafe: false,
+
+  setAppURI: function(aURI) {
+    throw Cr.NS_ERROR_NOT_IMPLEMENTED;
+  }
+};
+
+this.NSGetFactory = XPCOMUtils.generateNSGetFactory([AppProtocolHandler]);

new file mode 100644
--- /dev/null
+++ b/netwerk/protocol/app/AppProtocolHandler.manifest
@@ -0,0 +1,3 @@
+# AppProtocolHander.js
+component {b7ad6144-d344-4687-b2d0-b6b9dce1f07f} AppProtocolHandler.js
+contract @mozilla.org/network/protocol;1?name=app {b7ad6144-d344-4687-b2d0-b6b9dce1f07f}

deleted file mode 100644
--- a/netwerk/protocol/app/Makefile.in
+++ /dev/null
@@ -1,9 +0,0 @@
-#
-# This Source Code Form is subject to the terms of the Mozilla Public
-# 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/.
-
-LOCAL_INCLUDES = \
-  -I$(srcdir)/../../base/src \
-  -I$(srcdir)/../../../modules/libjar \
-  $(NULL)

--- a/netwerk/protocol/app/moz.build
+++ b/netwerk/protocol/app/moz.build
@@ -1,18 +1,10 @@
 # -*- Mode: python; c-basic-offset: 4; indent-tabs-mode: nil; tab-width: 40 -*-
 # vim: set filetype=python:
 # This Source Code Form is subject to the terms of the Mozilla Public
 # 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/.
 
-MODULE = 'necko'
-
-SOURCES += [
-    'AppProtocolHandler.cpp',
+EXTRA_COMPONENTS += [
+    'AppProtocolHandler.js',
+    'AppProtocolHandler.manifest',
 ]
-
-LIBRARY_NAME = 'nkapp_s'
-
-FAIL_ON_WARNINGS = True
-
-LIBXUL_LIBRARY = True
-