--- a/toolkit/components/build/nsToolkitCompsCID.h
+++ b/toolkit/components/build/nsToolkitCompsCID.h
@@ -87,16 +87,19 @@
 #endif
 
 #define NS_ADDONCONTENTPOLICY_CONTRACTID \
   "@mozilla.org/addons/content-policy;1"
 
 #define NS_ADDONPATHSERVICE_CONTRACTID \
     "@mozilla.org/addon-path-service;1"
 
+#define NS_WEBREQUESTSERVICE_CONTRACTID \
+  "@mozilla.org/addons/webrequest-service;1"
+
 /////////////////////////////////////////////////////////////////////////////
 
 #define ALERT_NOTIFICATION_CID \
 { 0x9a7b7a41, 0x0b47, 0x47f7, { 0xb6, 0x1b, 0x15, 0xa2, 0x10, 0xd6, 0xf0, 0x20 } }
 
 // {A0CCAAF8-09DA-44D8-B250-9AC3E93C8117}
 #define NS_ALERTSSERVICE_CID \
 { 0xa0ccaaf8, 0x9da, 0x44d8, { 0xb2, 0x50, 0x9a, 0xc3, 0xe9, 0x3c, 0x81, 0x17 } }
@@ -187,8 +190,12 @@
 #define NS_ADDON_PATH_SERVICE_CID \
 { 0xa39f39d0, 0xdfb6, 0x11e3, { 0x8b, 0x68, 0x08, 0x00, 0x20, 0x0c, 0x9a, 0x66 } }
 
 #define NS_ADDON_POLICY_SERVICE_CID \
 { 0x562de129, 0x8338, 0x482c, { 0xbb, 0x96, 0xa1, 0xff, 0x09, 0xee, 0x53, 0xcc } }
 
 #define NS_ADDON_POLICY_SERVICE_CONTRACTID \
   "@mozilla.org/addons/policy-service;1"
+
+// {5dd0c968-d74d-42c3-b930-36145f885c3b}
+#define NS_WEBREQUEST_SERVICE_CID \
+{ 0x5dd0c968, 0xd74d, 0x42c3, { 0xb9, 0x30, 0x36, 0x14, 0x5f, 0x88, 0x5c, 0x3b } }

--- a/toolkit/components/build/nsToolkitCompsModule.cpp
+++ b/toolkit/components/build/nsToolkitCompsModule.cpp
@@ -33,16 +33,17 @@
 
 #include "nsBrowserStatusFilter.h"
 #include "mozilla/FinalizationWitnessService.h"
 #include "mozilla/NativeOSFileInternals.h"
 #include "mozilla/AddonContentPolicy.h"
 #include "mozilla/AddonManagerStartup.h"
 #include "mozilla/AddonPathService.h"
 #include "mozilla/ExtensionPolicyService.h"
+#include "mozilla/WebRequestService.h"
 
 #if defined(XP_WIN)
 #include "NativeFileWatcherWin.h"
 #else
 #include "NativeFileWatcherNotSupported.h"
 #endif // (XP_WIN)
 
 #include "nsWebRequestListener.h"
@@ -123,16 +124,17 @@ NS_GENERIC_FACTORY_CONSTRUCTOR(nsUpdateP
 NS_GENERIC_FACTORY_CONSTRUCTOR_INIT(FinalizationWitnessService, Init)
 NS_GENERIC_FACTORY_CONSTRUCTOR(NativeOSFileInternalsService)
 NS_GENERIC_FACTORY_CONSTRUCTOR_INIT(NativeFileWatcherService, Init)
 
 NS_GENERIC_FACTORY_CONSTRUCTOR(AddonContentPolicy)
 NS_GENERIC_FACTORY_SINGLETON_CONSTRUCTOR(AddonPathService, AddonPathService::GetInstance)
 NS_GENERIC_FACTORY_SINGLETON_CONSTRUCTOR(AddonManagerStartup, AddonManagerStartup::GetInstance)
 NS_GENERIC_FACTORY_SINGLETON_CONSTRUCTOR(ExtensionPolicyService, ExtensionPolicyService::GetInstance)
+NS_GENERIC_FACTORY_SINGLETON_CONSTRUCTOR(WebRequestService, WebRequestService::GetInstance)
 
 NS_GENERIC_FACTORY_CONSTRUCTOR(nsWebRequestListener)
 
 NS_DEFINE_NAMED_CID(NS_TOOLKIT_APPSTARTUP_CID);
 #if defined(MOZ_HAS_PERFSTATS)
 NS_DEFINE_NAMED_CID(NS_TOOLKIT_PERFORMANCESTATSSERVICE_CID);
 #endif // defined (MOZ_HAS_PERFSTATS)
 
@@ -159,16 +161,17 @@ NS_DEFINE_NAMED_CID(NS_BROWSERSTATUSFILT
 NS_DEFINE_NAMED_CID(NS_UPDATEPROCESSOR_CID);
 #endif
 NS_DEFINE_NAMED_CID(FINALIZATIONWITNESSSERVICE_CID);
 NS_DEFINE_NAMED_CID(NATIVE_OSFILE_INTERNALS_SERVICE_CID);
 NS_DEFINE_NAMED_CID(NS_ADDONCONTENTPOLICY_CID);
 NS_DEFINE_NAMED_CID(NS_ADDON_PATH_SERVICE_CID);
 NS_DEFINE_NAMED_CID(NS_ADDON_MANAGER_STARTUP_CID);
 NS_DEFINE_NAMED_CID(NS_ADDON_POLICY_SERVICE_CID);
+NS_DEFINE_NAMED_CID(NS_WEBREQUEST_SERVICE_CID);
 NS_DEFINE_NAMED_CID(NATIVE_FILEWATCHER_SERVICE_CID);
 NS_DEFINE_NAMED_CID(NS_WEBREQUESTLISTENER_CID);
 
 static const Module::CIDEntry kToolkitCIDs[] = {
   { &kNS_TOOLKIT_APPSTARTUP_CID, false, nullptr, nsAppStartupConstructor },
 #if defined(MOZ_HAS_TERMINATOR)
   { &kNS_TOOLKIT_TERMINATOR_CID, false, nullptr, nsTerminatorConstructor },
 #endif
@@ -195,16 +198,17 @@ static const Module::CIDEntry kToolkitCI
   { &kNS_UPDATEPROCESSOR_CID, false, nullptr, nsUpdateProcessorConstructor },
 #endif
   { &kFINALIZATIONWITNESSSERVICE_CID, false, nullptr, FinalizationWitnessServiceConstructor },
   { &kNATIVE_OSFILE_INTERNALS_SERVICE_CID, false, nullptr, NativeOSFileInternalsServiceConstructor },
   { &kNS_ADDONCONTENTPOLICY_CID, false, nullptr, AddonContentPolicyConstructor },
   { &kNS_ADDON_PATH_SERVICE_CID, false, nullptr, AddonPathServiceConstructor },
   { &kNS_ADDON_MANAGER_STARTUP_CID, false, nullptr, AddonManagerStartupConstructor },
   { &kNS_ADDON_POLICY_SERVICE_CID, false, nullptr, ExtensionPolicyServiceConstructor },
+  { &kNS_WEBREQUEST_SERVICE_CID, false, nullptr, WebRequestServiceConstructor },
   { &kNATIVE_FILEWATCHER_SERVICE_CID, false, nullptr, NativeFileWatcherServiceConstructor },
   { &kNS_WEBREQUESTLISTENER_CID, false, nullptr, nsWebRequestListenerConstructor },
   { nullptr }
 };
 
 static const Module::ContractIDEntry kToolkitContracts[] = {
   { NS_APPSTARTUP_CONTRACTID, &kNS_TOOLKIT_APPSTARTUP_CID },
 #if defined(MOZ_HAS_TERMINATOR)
@@ -234,16 +238,17 @@ static const Module::ContractIDEntry kTo
   { NS_UPDATEPROCESSOR_CONTRACTID, &kNS_UPDATEPROCESSOR_CID },
 #endif
   { FINALIZATIONWITNESSSERVICE_CONTRACTID, &kFINALIZATIONWITNESSSERVICE_CID },
   { NATIVE_OSFILE_INTERNALS_SERVICE_CONTRACTID, &kNATIVE_OSFILE_INTERNALS_SERVICE_CID },
   { NS_ADDONCONTENTPOLICY_CONTRACTID, &kNS_ADDONCONTENTPOLICY_CID },
   { NS_ADDONPATHSERVICE_CONTRACTID, &kNS_ADDON_PATH_SERVICE_CID },
   { NS_ADDONMANAGERSTARTUP_CONTRACTID, &kNS_ADDON_MANAGER_STARTUP_CID },
   { NS_ADDON_POLICY_SERVICE_CONTRACTID, &kNS_ADDON_POLICY_SERVICE_CID },
+  { NS_WEBREQUESTSERVICE_CONTRACTID, &kNS_WEBREQUEST_SERVICE_CID },
   { NATIVE_FILEWATCHER_SERVICE_CONTRACTID, &kNATIVE_FILEWATCHER_SERVICE_CID },
   { NS_WEBREQUESTLISTENER_CONTRACTID, &kNS_WEBREQUESTLISTENER_CID },
   { nullptr }
 };
 
 static const mozilla::Module::CategoryEntry kToolkitCategories[] = {
   { "content-policy", NS_ADDONCONTENTPOLICY_CONTRACTID, NS_ADDONCONTENTPOLICY_CONTRACTID },
   { nullptr }

--- a/toolkit/components/extensions/moz.build
+++ b/toolkit/components/extensions/moz.build
@@ -1,14 +1,15 @@
 # -*- Mode: python; 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/.
 
+
 with Files('**'):
     BUG_COMPONENT = ('Toolkit', 'WebExtensions: General')
 
 EXTRA_JS_MODULES += [
     'Extension.jsm',
     'ExtensionChild.jsm',
     'ExtensionChildDevToolsUtils.jsm',
     'ExtensionCommon.jsm',

new file mode 100644
--- /dev/null
+++ b/toolkit/components/extensions/webrequest/WebRequestService.cpp
@@ -0,0 +1,151 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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 "WebRequestService.h"
+
+#include "mozilla/Assertions.h"
+#include "mozilla/ClearOnShutdown.h"
+#include "nsCOMPtr.h"
+#include "nsIChannel.h"
+#include "nsIDOMWindowUtils.h"
+#include "nsISupports.h"
+#include "nsITabParent.h"
+#include "nsITraceableChannel.h"
+
+#include "mozilla/dom/TabParent.h"
+
+using namespace mozilla;
+using namespace mozilla::dom;
+
+WebRequestService::WebRequestService()
+  : mDataLock("WebRequest service data lock")
+{
+}
+
+WebRequestService::~WebRequestService()
+{
+}
+
+NS_IMPL_ISUPPORTS(WebRequestService, mozIWebRequestService)
+
+/* static */ WebRequestService*
+WebRequestService::GetInstance()
+{
+  static RefPtr<WebRequestService> instance;
+  if (!instance) {
+    instance = new WebRequestService();
+    ClearOnShutdown(&instance);
+  }
+  return instance;
+}
+
+
+NS_IMETHODIMP
+WebRequestService::RegisterTraceableChannel(uint64_t aChannelId,
+                                            nsIChannel* aChannel,
+                                            const nsAString& aAddonId,
+                                            nsITabParent* aTabParent,
+                                            nsIJSRAIIHelper** aHelper)
+{
+  nsCOMPtr<nsITraceableChannel> traceableChannel = do_QueryInterface(aChannel);
+  NS_ENSURE_TRUE(traceableChannel, NS_ERROR_INVALID_ARG);
+
+  nsCOMPtr<nsIAtom> addonId = NS_Atomize(aAddonId);
+  ChannelParent* entry = new ChannelParent(aChannelId, aChannel,
+                                           addonId, aTabParent);
+
+  RefPtr<Destructor> destructor = new Destructor(entry);
+  destructor.forget(aHelper);
+
+  return NS_OK;
+}
+
+already_AddRefed<nsIChannel>
+WebRequestService::GetTraceableChannel(uint64_t aChannelId,
+                                       nsIAtom* aAddonId,
+                                       nsIContentParent* aContentParent)
+{
+  MutexAutoLock al(mDataLock);
+
+  auto entry = mChannelEntries.Get(aChannelId);
+  if (!entry) {
+    return nullptr;
+  }
+
+  for (auto channelEntry : entry->mTabParents) {
+    nsIContentParent* contentParent = nullptr;
+    if (channelEntry->mTabParent) {
+      contentParent = static_cast<nsIContentParent*>(
+        channelEntry->mTabParent->Manager());
+    }
+
+    if (channelEntry->mAddonId == aAddonId && contentParent == aContentParent) {
+      nsCOMPtr<nsIChannel> channel = do_QueryReferent(entry->mChannel);
+      return channel.forget();
+    }
+  }
+
+  return nullptr;
+}
+
+
+WebRequestService::ChannelParent::ChannelParent(uint64_t aChannelId, nsIChannel* aChannel,
+                                                nsIAtom* aAddonId, nsITabParent* aTabParent)
+  : mTabParent(static_cast<TabParent*>(aTabParent))
+  , mAddonId(aAddonId)
+  , mChannelId(aChannelId)
+{
+  auto service = GetInstance();
+  MutexAutoLock al(service->mDataLock);
+
+  auto entry = service->mChannelEntries.LookupOrAdd(mChannelId);
+
+  entry->mChannel = do_GetWeakReference(aChannel);
+  entry->mTabParents.insertBack(this);
+}
+
+WebRequestService::ChannelParent::~ChannelParent()
+{}
+
+void
+WebRequestService::ChannelParent::Detach()
+{
+  auto service = GetInstance();
+  MutexAutoLock al(service->mDataLock);
+
+  auto& map = service->mChannelEntries;
+  auto entry = map.Get(mChannelId);
+  MOZ_ASSERT(entry);
+
+  removeFrom(entry->mTabParents);
+  if (entry->mTabParents.isEmpty()) {
+    map.Remove(mChannelId);
+  }
+}
+
+WebRequestService::Destructor::~Destructor()
+{
+  MOZ_ASSERT(mDestructCalled);
+  if (!mDestructCalled) {
+    Destruct();
+  }
+}
+
+NS_IMETHODIMP
+WebRequestService::Destructor::Destruct()
+{
+  if (NS_WARN_IF(mDestructCalled)) {
+    return NS_ERROR_FAILURE;
+  }
+  mDestructCalled = true;
+
+  mChannelParent->Detach();
+  delete mChannelParent;
+
+  return NS_OK;
+}
+
+NS_IMPL_ISUPPORTS(WebRequestService::Destructor, nsIJSRAIIHelper)

new file mode 100644
--- /dev/null
+++ b/toolkit/components/extensions/webrequest/WebRequestService.h
@@ -0,0 +1,97 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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 mozilla_WebRequestService_h
+#define mozilla_WebRequestService_h
+
+#include "mozIWebRequestService.h"
+
+#include "mozilla/LinkedList.h"
+#include "mozilla/Mutex.h"
+#include "nsCOMPtr.h"
+#include "nsHashKeys.h"
+#include "nsClassHashtable.h"
+#include "nsIAtom.h"
+#include "nsIDOMWindowUtils.h"
+#include "nsWeakPtr.h"
+
+using namespace mozilla;
+
+namespace mozilla {
+namespace dom {
+  class TabParent;
+  class nsIContentParent;
+}
+}
+
+class WebRequestService : public mozIWebRequestService
+{
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_MOZIWEBREQUESTSERVICE
+
+  explicit WebRequestService();
+
+  static WebRequestService*
+  GetInstance();
+
+  already_AddRefed<nsIChannel>
+  GetTraceableChannel(uint64_t aChannelId, nsIAtom* aAddonId,
+                      dom::nsIContentParent* aContentParent);
+
+protected:
+  virtual ~WebRequestService();
+
+private:
+  class ChannelParent : public LinkedListElement<ChannelParent>
+  {
+  public:
+    explicit ChannelParent(uint64_t aChannelId, nsIChannel* aChannel, nsIAtom* aAddonId, nsITabParent* aTabParent);
+    ~ChannelParent();
+
+    void Detach();
+
+    const RefPtr<dom::TabParent> mTabParent;
+    const nsCOMPtr<nsIAtom> mAddonId;
+
+  private:
+    const uint64_t mChannelId;
+  };
+
+  class Destructor : public nsIJSRAIIHelper
+  {
+  public:
+    NS_DECL_ISUPPORTS
+    NS_DECL_NSIJSRAIIHELPER
+
+    explicit Destructor(ChannelParent* aChannelParent)
+      : mChannelParent(aChannelParent)
+      , mDestructCalled(false)
+    {}
+
+  protected:
+    virtual ~Destructor();
+
+  private:
+    ChannelParent* mChannelParent;
+    bool mDestructCalled;
+  };
+
+  class ChannelEntry
+  {
+  public:
+    // Note: We can't keep a strong pointer to the channel here, since channels
+    // are not cycle collected, and a reference to this object will be stored on
+    // the channel in order to keep the entry alive.
+    nsWeakPtr mChannel;
+    LinkedList<ChannelParent> mTabParents;
+  };
+
+  nsClassHashtable<nsUint64HashKey, ChannelEntry> mChannelEntries;
+  Mutex mDataLock;
+};
+
+#endif // mozilla_WebRequestService_h

--- a/toolkit/components/extensions/webrequest/moz.build
+++ b/toolkit/components/extensions/webrequest/moz.build
@@ -1,21 +1,30 @@
 # -*- Mode: python; 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/.
 
 XPIDL_SOURCES += [
+    'mozIWebRequestService.idl',
     'nsIWebRequestListener.idl',
 ]
 
 XPIDL_MODULE = 'webextensions'
 
+UNIFIED_SOURCES += [
+    'nsWebRequestListener.cpp',
+    'WebRequestService.cpp',
+]
+
 EXPORTS += [
     'nsWebRequestListener.h',
 ]
 
-UNIFIED_SOURCES += [
-    'nsWebRequestListener.cpp',
+EXPORTS.mozilla += [
+    'WebRequestService.h',
 ]
 
-FINAL_LIBRARY = 'xul'
\ No newline at end of file
+FINAL_LIBRARY = 'xul'
+
+with Files("**"):
+    BUG_COMPONENT = ("Toolkit", "WebExtensions: Request Handling")

new file mode 100644
--- /dev/null
+++ b/toolkit/components/extensions/webrequest/mozIWebRequestService.idl
@@ -0,0 +1,18 @@
+/* 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 "nsISupports.idl"
+
+interface nsIChannel;
+interface nsIJSRAIIHelper;
+interface nsITabParent;
+
+[scriptable, builtinclass, uuid(1b1118ed-f208-4cfc-b841-5b31a78c2b7a)]
+interface mozIWebRequestService : nsISupports
+{
+  nsIJSRAIIHelper registerTraceableChannel(in uint64_t channelId,
+                                           in nsIChannel channel,
+                                           in AString addonId,
+                                           [optional] in nsITabParent tabParent);
+};