diff --git a/dom/audiochannel/AudioChannelService.cpp b/dom/audiochannel/AudioChannelService.cpp
index 685593d1bddf..c448057815ef 100644
--- a/dom/audiochannel/AudioChannelService.cpp
+++ b/dom/audiochannel/AudioChannelService.cpp
@@ -330,8 +330,7 @@ AudioChannelService::IsEnableAudioCompeting()
 }
 
 NS_INTERFACE_MAP_BEGIN(AudioChannelService)
-  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIAudioChannelService)
-  NS_INTERFACE_MAP_ENTRY(nsIAudioChannelService)
+  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIObserver)
   NS_INTERFACE_MAP_ENTRY(nsIObserver)
 NS_INTERFACE_MAP_END
 
@@ -666,32 +665,6 @@ AudioChannelService::Observe(nsISupports* aSubject, const char* aTopic,
   return NS_OK;
 }
 
-void
-AudioChannelService::RefreshAgentsVolumeAndPropagate(AudioChannel aAudioChannel,
-                                                     nsPIDOMWindowOuter* aWindow)
-{
-  MOZ_ASSERT(aWindow);
-  MOZ_ASSERT(aWindow->IsOuterWindow());
-
-  nsCOMPtr<nsPIDOMWindowOuter> topWindow = aWindow->GetScriptableTop();
-  if (!topWindow) {
-    return;
-  }
-
-  AudioChannelWindow* winData = GetWindowData(topWindow->WindowID());
-  if (!winData) {
-    return;
-  }
-
-  for (uint32_t i = 0; i < mTabParents.Length(); ++i) {
-    mTabParents[i]->AudioChannelChangeNotification(aWindow, aAudioChannel,
-                                                   winData->mChannels[(uint32_t)aAudioChannel].mVolume,
-                                                   winData->mChannels[(uint32_t)aAudioChannel].mMuted);
-  }
-
-  RefreshAgentsVolume(aWindow);
-}
-
 void
 AudioChannelService::RefreshAgents(nsPIDOMWindowOuter* aWindow,
                                    const std::function<void(AudioChannelAgent*)>& aFunc)
@@ -869,162 +842,6 @@ AudioChannelService::GetWindowData(uint64_t aWindowID) const
   return nullptr;
 }
 
-float
-AudioChannelService::GetAudioChannelVolume(nsPIDOMWindowOuter* aWindow,
-                                           AudioChannel aAudioChannel)
-{
-  MOZ_ASSERT(NS_IsMainThread());
-  MOZ_ASSERT(aWindow);
-  MOZ_ASSERT(aWindow->IsOuterWindow());
-
-  AudioChannelWindow* winData = GetOrCreateWindowData(aWindow);
-  return winData->mChannels[(uint32_t)aAudioChannel].mVolume;
-}
-
-NS_IMETHODIMP
-AudioChannelService::GetAudioChannelVolume(mozIDOMWindowProxy* aWindow,
-                                           unsigned short aAudioChannel,
-                                           float* aVolume)
-{
-  MOZ_ASSERT(NS_IsMainThread());
-
-  auto* window = nsPIDOMWindowOuter::From(aWindow)->GetScriptableTop();
-  if (!window) {
-    *aVolume = 0.f;
-    return NS_ERROR_FAILURE;
-  }
-  *aVolume = GetAudioChannelVolume(window, (AudioChannel)aAudioChannel);
-  return NS_OK;
-}
-
-void
-AudioChannelService::SetAudioChannelVolume(nsPIDOMWindowOuter* aWindow,
-                                           AudioChannel aAudioChannel,
-                                           float aVolume)
-{
-  MOZ_ASSERT(NS_IsMainThread());
-  MOZ_ASSERT(aWindow);
-  MOZ_ASSERT(aWindow->IsOuterWindow());
-
-  MOZ_LOG(GetAudioChannelLog(), LogLevel::Debug,
-         ("AudioChannelService, SetAudioChannelVolume, window = %p, type = %" PRIu32 ", "
-          "volume = %f\n", aWindow, static_cast<uint32_t>(aAudioChannel), aVolume));
-
-  AudioChannelWindow* winData = GetOrCreateWindowData(aWindow);
-  winData->mChannels[(uint32_t)aAudioChannel].mVolume = aVolume;
-  RefreshAgentsVolumeAndPropagate(aAudioChannel, aWindow);
-}
-
-NS_IMETHODIMP
-AudioChannelService::SetAudioChannelVolume(mozIDOMWindowProxy* aWindow,
-                                           unsigned short aAudioChannel,
-                                           float aVolume)
-{
-  MOZ_ASSERT(NS_IsMainThread());
-
-  auto* window = nsPIDOMWindowOuter::From(aWindow)->GetScriptableTop();
-  if (!window) {
-    return NS_ERROR_FAILURE;
-  }
-  SetAudioChannelVolume(window, (AudioChannel)aAudioChannel, aVolume);
-  return NS_OK;
-}
-
-bool
-AudioChannelService::GetAudioChannelMuted(nsPIDOMWindowOuter* aWindow,
-                                          AudioChannel aAudioChannel)
-{
-  MOZ_ASSERT(NS_IsMainThread());
-  MOZ_ASSERT(aWindow);
-  MOZ_ASSERT(aWindow->IsOuterWindow());
-
-  AudioChannelWindow* winData = GetOrCreateWindowData(aWindow);
-  return winData->mChannels[(uint32_t)aAudioChannel].mMuted;
-}
-
-NS_IMETHODIMP
-AudioChannelService::GetAudioChannelMuted(mozIDOMWindowProxy* aWindow,
-                                          unsigned short aAudioChannel,
-                                          bool* aMuted)
-{
-  MOZ_ASSERT(NS_IsMainThread());
-
-  auto* window = nsPIDOMWindowOuter::From(aWindow)->GetScriptableTop();
-  if (!window) {
-    *aMuted = false;
-    return NS_ERROR_FAILURE;
-  }
-  *aMuted = GetAudioChannelMuted(window, (AudioChannel)aAudioChannel);
-  return NS_OK;
-}
-
-void
-AudioChannelService::SetAudioChannelMuted(nsPIDOMWindowOuter* aWindow,
-                                          AudioChannel aAudioChannel,
-                                          bool aMuted)
-{
-  MOZ_ASSERT(NS_IsMainThread());
-  MOZ_ASSERT(aWindow);
-  MOZ_ASSERT(aWindow->IsOuterWindow());
-
-  MOZ_LOG(GetAudioChannelLog(), LogLevel::Debug,
-         ("AudioChannelService, SetAudioChannelMuted, window = %p, type = %" PRIu32 ", "
-          "mute = %s\n", aWindow, static_cast<uint32_t>(aAudioChannel),
-          aMuted ? "true" : "false"));
-
-  if (aAudioChannel == AudioChannel::System) {
-    // Workaround for bug1183033, system channel type can always playback.
-    return;
-  }
-
-  AudioChannelWindow* winData = GetOrCreateWindowData(aWindow);
-  winData->mChannels[(uint32_t)aAudioChannel].mMuted = aMuted;
-  RefreshAgentsVolumeAndPropagate(aAudioChannel, aWindow);
-}
-
-NS_IMETHODIMP
-AudioChannelService::SetAudioChannelMuted(mozIDOMWindowProxy* aWindow,
-                                          unsigned short aAudioChannel,
-                                          bool aMuted)
-{
-  MOZ_ASSERT(NS_IsMainThread());
-
-  auto* window = nsPIDOMWindowOuter::From(aWindow)->GetScriptableTop();
-  if (!window) {
-    return NS_ERROR_FAILURE;
-  }
-  SetAudioChannelMuted(window, (AudioChannel)aAudioChannel, aMuted);
-  return NS_OK;
-}
-
-bool
-AudioChannelService::IsAudioChannelActive(nsPIDOMWindowOuter* aWindow,
-                                          AudioChannel aAudioChannel)
-{
-  MOZ_ASSERT(NS_IsMainThread());
-  MOZ_ASSERT(aWindow);
-  MOZ_ASSERT(aWindow->IsOuterWindow());
-
-  AudioChannelWindow* winData = GetOrCreateWindowData(aWindow);
-  return !!winData->mChannels[(uint32_t)aAudioChannel].mNumberOfAgents;
-}
-
-NS_IMETHODIMP
-AudioChannelService::IsAudioChannelActive(mozIDOMWindowProxy* aWindow,
-                                          unsigned short aAudioChannel,
-                                          bool* aActive)
-{
-  MOZ_ASSERT(NS_IsMainThread());
-
-  auto* window = nsPIDOMWindowOuter::From(aWindow)->GetScriptableTop();
-  if (!window) {
-    *aActive = false;
-    return NS_ERROR_FAILURE;
-  }
-  *aActive = IsAudioChannelActive(window, (AudioChannel)aAudioChannel);
-  return NS_OK;
-}
-
 bool
 AudioChannelService::IsWindowActive(nsPIDOMWindowOuter* aWindow)
 {
diff --git a/dom/audiochannel/AudioChannelService.h b/dom/audiochannel/AudioChannelService.h
index e36a37046a28..651f718b51a4 100644
--- a/dom/audiochannel/AudioChannelService.h
+++ b/dom/audiochannel/AudioChannelService.h
@@ -7,7 +7,6 @@
 #ifndef mozilla_dom_audiochannelservice_h__
 #define mozilla_dom_audiochannelservice_h__
 
-#include "nsIAudioChannelService.h"
 #include "nsAutoPtr.h"
 #include "nsIObserver.h"
 #include "nsTObserverArray.h"
@@ -58,13 +57,11 @@ public:
   uint32_t mSuspend;
 };
 
-class AudioChannelService final : public nsIAudioChannelService
-                                , public nsIObserver
+class AudioChannelService final : public nsIObserver
 {
 public:
   NS_DECL_ISUPPORTS
   NS_DECL_NSIOBSERVER
-  NS_DECL_NSIAUDIOCHANNELSERVICE
 
   /**
    * eNotAudible : agent is not audible
@@ -142,19 +139,6 @@ public:
                            AudibleState aAudible,
                            AudibleChangedReasons aReason);
 
-  /* Methods for the BrowserElementAudioChannel */
-  float GetAudioChannelVolume(nsPIDOMWindowOuter* aWindow, AudioChannel aChannel);
-
-  void SetAudioChannelVolume(nsPIDOMWindowOuter* aWindow, AudioChannel aChannel,
-                             float aVolume);
-
-  bool GetAudioChannelMuted(nsPIDOMWindowOuter* aWindow, AudioChannel aChannel);
-
-  void SetAudioChannelMuted(nsPIDOMWindowOuter* aWindow, AudioChannel aChannel,
-                            bool aMuted);
-
-  bool IsAudioChannelActive(nsPIDOMWindowOuter* aWindow, AudioChannel aChannel);
-
   bool IsWindowActive(nsPIDOMWindowOuter* aWindow);
 
   /**
@@ -184,9 +168,6 @@ public:
   void RefreshAgentsSuspend(nsPIDOMWindowOuter* aWindow,
                             nsSuspendedTypes aSuspend);
 
-  void RefreshAgentsVolumeAndPropagate(AudioChannel aAudioChannel,
-                                       nsPIDOMWindowOuter* aWindow);
-
   // This method needs to know the inner window that wants to capture audio. We
   // group agents per top outer window, but we can have multiple innerWindow per
   // top outerWindow (subiframes, etc.) and we have to identify all the agents
@@ -254,10 +235,7 @@ private:
       , mIsAudioCaptured(false)
       , mOwningAudioFocus(!AudioChannelService::IsEnableAudioCompeting())
       , mShouldSendBlockStopEvent(false)
-    {
-      // Workaround for bug1183033, system channel type can always playback.
-      mChannels[(int16_t)AudioChannel::System].mMuted = false;
-    }
+    {}
 
     void AudioFocusChanged(AudioChannelAgent* aNewPlayingAgent);
     void AudioAudibleChanged(AudioChannelAgent* aAgent,
diff --git a/dom/audiochannel/moz.build b/dom/audiochannel/moz.build
index d4b02a35e15f..9eda18aa1e90 100644
--- a/dom/audiochannel/moz.build
+++ b/dom/audiochannel/moz.build
@@ -9,7 +9,6 @@ with Files("**"):
 
 XPIDL_SOURCES += [
     'nsIAudioChannelAgent.idl',
-    'nsIAudioChannelService.idl',
 ]
 
 XPIDL_MODULE = 'dom_audiochannel'
diff --git a/dom/audiochannel/nsIAudioChannelService.idl b/dom/audiochannel/nsIAudioChannelService.idl
deleted file mode 100644
index 2c154a84b3e2..000000000000
--- a/dom/audiochannel/nsIAudioChannelService.idl
+++ /dev/null
@@ -1,29 +0,0 @@
-/* -*- Mode: IDL; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
-/* 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 mozIDOMWindowProxy;
-
-[scriptable, builtinclass, uuid(5cb24dbc-36c7-46a4-9966-ac73141dc795)]
-interface nsIAudioChannelService : nsISupports
-{
-  float getAudioChannelVolume(in mozIDOMWindowProxy window,
-                              in unsigned short audioChannel);
-
-  void setAudioChannelVolume(in mozIDOMWindowProxy window,
-                             in unsigned short audioChannel,
-                             in float volume);
-
-  boolean getAudioChannelMuted(in mozIDOMWindowProxy window,
-                               in unsigned short audioChannel);
-
-  void setAudioChannelMuted(in mozIDOMWindowProxy window,
-                            in unsigned short audioChannel,
-                            in boolean muted);
-
-  boolean isAudioChannelActive(in mozIDOMWindowProxy window,
-                               in unsigned short audioChannel);
-};
diff --git a/dom/browser-element/BrowserElementChildPreload.js b/dom/browser-element/BrowserElementChildPreload.js
index 80e5707f26e0..e6785fe1b0c7 100644
--- a/dom/browser-element/BrowserElementChildPreload.js
+++ b/dom/browser-element/BrowserElementChildPreload.js
@@ -18,9 +18,6 @@ Cu.import("resource://gre/modules/Services.jsm");
 Cu.import("resource://gre/modules/BrowserElementPromptService.jsm");
 Cu.import("resource://gre/modules/Task.jsm");
 
-XPCOMUtils.defineLazyServiceGetter(this, "acs",
-                                   "@mozilla.org/audiochannel/service;1",
-                                   "nsIAudioChannelService");
 XPCOMUtils.defineLazyModuleGetter(this, "ManifestFinder",
                                   "resource://gre/modules/ManifestFinder.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "ManifestObtainer",
@@ -316,11 +313,6 @@ BrowserElementChild.prototype = {
       "find-next": this._recvFindNext,
       "clear-match": this._recvClearMatch,
       "execute-script": this._recvExecuteScript,
-      "get-audio-channel-volume": this._recvGetAudioChannelVolume,
-      "set-audio-channel-volume": this._recvSetAudioChannelVolume,
-      "get-audio-channel-muted": this._recvGetAudioChannelMuted,
-      "set-audio-channel-muted": this._recvSetAudioChannelMuted,
-      "get-is-audio-channel-active": this._recvIsAudioChannelActive,
       "get-web-manifest": this._recvGetWebManifest,
     }
 
@@ -1381,54 +1373,6 @@ BrowserElementChild.prototype = {
     docShell.contentViewer.fullZoom = data.json.zoom;
   },
 
-  _recvGetAudioChannelVolume: function(data) {
-    debug("Received getAudioChannelVolume message: (" + data.json.id + ")");
-
-    let volume = acs.getAudioChannelVolume(content,
-                                           data.json.args.audioChannel);
-    sendAsyncMsg('got-audio-channel-volume', {
-      id: data.json.id, successRv: volume
-    });
-  },
-
-  _recvSetAudioChannelVolume: function(data) {
-    debug("Received setAudioChannelVolume message: (" + data.json.id + ")");
-
-    acs.setAudioChannelVolume(content,
-                              data.json.args.audioChannel,
-                              data.json.args.volume);
-    sendAsyncMsg('got-set-audio-channel-volume', {
-      id: data.json.id, successRv: true
-    });
-  },
-
-  _recvGetAudioChannelMuted: function(data) {
-    debug("Received getAudioChannelMuted message: (" + data.json.id + ")");
-
-    let muted = acs.getAudioChannelMuted(content, data.json.args.audioChannel);
-    sendAsyncMsg('got-audio-channel-muted', {
-      id: data.json.id, successRv: muted
-    });
-  },
-
-  _recvSetAudioChannelMuted: function(data) {
-    debug("Received setAudioChannelMuted message: (" + data.json.id + ")");
-
-    acs.setAudioChannelMuted(content, data.json.args.audioChannel,
-                             data.json.args.muted);
-    sendAsyncMsg('got-set-audio-channel-muted', {
-      id: data.json.id, successRv: true
-    });
-  },
-
-  _recvIsAudioChannelActive: function(data) {
-    debug("Received isAudioChannelActive message: (" + data.json.id + ")");
-
-    let active = acs.isAudioChannelActive(content, data.json.args.audioChannel);
-    sendAsyncMsg('got-is-audio-channel-active', {
-      id: data.json.id, successRv: active
-    });
-  },
   _recvGetWebManifest: Task.async(function* (data) {
     debug(`Received GetWebManifest message: (${data.json.id})`);
     let manifest = null;
diff --git a/dom/browser-element/BrowserElementParent.js b/dom/browser-element/BrowserElementParent.js
index e07774983770..c4486f5da805 100644
--- a/dom/browser-element/BrowserElementParent.js
+++ b/dom/browser-element/BrowserElementParent.js
@@ -180,11 +180,6 @@ BrowserElementParent.prototype = {
       "caretstatechanged": this._handleCaretStateChanged,
       "findchange": this._handleFindChange,
       "execute-script-done": this._gotDOMRequestResult,
-      "got-audio-channel-volume": this._gotDOMRequestResult,
-      "got-set-audio-channel-volume": this._gotDOMRequestResult,
-      "got-audio-channel-muted": this._gotDOMRequestResult,
-      "got-set-audio-channel-muted": this._gotDOMRequestResult,
-      "got-is-audio-channel-active": this._gotDOMRequestResult,
       "got-web-manifest": this._gotDOMRequestResult,
     };
 
@@ -896,33 +891,6 @@ BrowserElementParent.prototype = {
     }
   },
 
-  getAudioChannelVolume: function(aAudioChannel) {
-    return this._sendDOMRequest('get-audio-channel-volume',
-                                {audioChannel: aAudioChannel});
-  },
-
-  setAudioChannelVolume: function(aAudioChannel, aVolume) {
-    return this._sendDOMRequest('set-audio-channel-volume',
-                                {audioChannel: aAudioChannel,
-                                 volume: aVolume});
-  },
-
-  getAudioChannelMuted: function(aAudioChannel) {
-    return this._sendDOMRequest('get-audio-channel-muted',
-                                {audioChannel: aAudioChannel});
-  },
-
-  setAudioChannelMuted: function(aAudioChannel, aMuted) {
-    return this._sendDOMRequest('set-audio-channel-muted',
-                                {audioChannel: aAudioChannel,
-                                 muted: aMuted});
-  },
-
-  isAudioChannelActive: function(aAudioChannel) {
-    return this._sendDOMRequest('get-is-audio-channel-active',
-                                {audioChannel: aAudioChannel});
-  },
-
   getWebManifest: defineDOMRequestMethod('get-web-manifest'),
   /**
    * Called when the visibility of the window which owns this iframe changes.
diff --git a/dom/browser-element/nsIBrowserElementAPI.idl b/dom/browser-element/nsIBrowserElementAPI.idl
index 159a0f400113..df0efa76b706 100644
--- a/dom/browser-element/nsIBrowserElementAPI.idl
+++ b/dom/browser-element/nsIBrowserElementAPI.idl
@@ -92,14 +92,6 @@ interface nsIBrowserElementAPI : nsISupports
   void addNextPaintListener(in nsIBrowserElementNextPaintListener listener);
   void removeNextPaintListener(in nsIBrowserElementNextPaintListener listener);
 
-  nsIDOMDOMRequest getAudioChannelVolume(in uint32_t audioChannel);
-  nsIDOMDOMRequest setAudioChannelVolume(in uint32_t audioChannel, in float volume);
-
-  nsIDOMDOMRequest getAudioChannelMuted(in uint32_t audioChannel);
-  nsIDOMDOMRequest setAudioChannelMuted(in uint32_t audioChannel, in bool muted);
-
-  nsIDOMDOMRequest isAudioChannelActive(in uint32_t audioChannel);
-
   nsIDOMDOMRequest executeScript(in DOMString script, in jsval options);
 
   /**
diff --git a/dom/ipc/PBrowser.ipdl b/dom/ipc/PBrowser.ipdl
index 6abab4fa0311..b6f479f37d95 100644
--- a/dom/ipc/PBrowser.ipdl
+++ b/dom/ipc/PBrowser.ipdl
@@ -827,13 +827,6 @@ child:
     async HandleAccessKey(WidgetKeyboardEvent event,
                           uint32_t[] charCodes, int32_t modifierMask);
 
-    /**
-     * Propagate a refresh to the child process
-     */
-    async AudioChannelChangeNotification(uint32_t aAudioChannel,
-                                         float aVolume,
-                                         bool aMuted);
-
     /**
      * Tells the root child docShell whether or not to use
      * global history. This is sent right after the PBrowser
diff --git a/dom/ipc/TabChild.cpp b/dom/ipc/TabChild.cpp
index fdabe8566968..c68445a11179 100644
--- a/dom/ipc/TabChild.cpp
+++ b/dom/ipc/TabChild.cpp
@@ -2321,27 +2321,6 @@ TabChild::RecvHandleAccessKey(const WidgetKeyboardEvent& aEvent,
   return IPC_OK();
 }
 
-mozilla::ipc::IPCResult
-TabChild::RecvAudioChannelChangeNotification(const uint32_t& aAudioChannel,
-                                             const float& aVolume,
-                                             const bool& aMuted)
-{
-  nsCOMPtr<nsPIDOMWindowOuter> window = do_GetInterface(WebNavigation());
-  if (window) {
-    RefPtr<AudioChannelService> service = AudioChannelService::GetOrCreate();
-    MOZ_ASSERT(service);
-
-    service->SetAudioChannelVolume(window,
-                                   static_cast<AudioChannel>(aAudioChannel),
-                                   aVolume);
-    service->SetAudioChannelMuted(window,
-                                  static_cast<AudioChannel>(aAudioChannel),
-                                  aMuted);
-  }
-
-  return IPC_OK();
-}
-
 mozilla::ipc::IPCResult
 TabChild::RecvSetUseGlobalHistory(const bool& aUse)
 {
diff --git a/dom/ipc/TabChild.h b/dom/ipc/TabChild.h
index ebf16eaedbb7..63be9dca00df 100644
--- a/dom/ipc/TabChild.h
+++ b/dom/ipc/TabChild.h
@@ -590,10 +590,6 @@ public:
                                                       nsTArray<uint32_t>&& aCharCodes,
                                                       const int32_t& aModifierMask) override;
 
-  virtual mozilla::ipc::IPCResult RecvAudioChannelChangeNotification(const uint32_t& aAudioChannel,
-                                                                     const float& aVolume,
-                                                                     const bool& aMuted) override;
-
   virtual mozilla::ipc::IPCResult RecvSetUseGlobalHistory(const bool& aUse) override;
 
   virtual mozilla::ipc::IPCResult RecvHandledWindowedPluginKeyEvent(
diff --git a/dom/ipc/TabParent.cpp b/dom/ipc/TabParent.cpp
index dfa880f781ff..5b594c7bb048 100644
--- a/dom/ipc/TabParent.cpp
+++ b/dom/ipc/TabParent.cpp
@@ -3217,33 +3217,6 @@ TabParent::GetShowInfo()
                   false, mDPI, mRounding, mDefaultScale.scale);
 }
 
-void
-TabParent::AudioChannelChangeNotification(nsPIDOMWindowOuter* aWindow,
-                                          AudioChannel aAudioChannel,
-                                          float aVolume,
-                                          bool aMuted)
-{
-  if (!mFrameElement || !mFrameElement->OwnerDoc()) {
-    return;
-  }
-
-  nsCOMPtr<nsPIDOMWindowOuter> window = mFrameElement->OwnerDoc()->GetWindow();
-  while (window) {
-    if (window == aWindow) {
-      Unused << SendAudioChannelChangeNotification(static_cast<uint32_t>(aAudioChannel),
-                                                   aVolume, aMuted);
-      break;
-    }
-
-    nsCOMPtr<nsPIDOMWindowOuter> win = window->GetScriptableParentOrNull();
-    if (!win) {
-      break;
-    }
-
-    window = win;
-  }
-}
-
 mozilla::ipc::IPCResult
 TabParent::RecvGetTabCount(uint32_t* aValue)
 {
diff --git a/dom/ipc/TabParent.h b/dom/ipc/TabParent.h
index 2ad73424fd10..11c4e115db5d 100644
--- a/dom/ipc/TabParent.h
+++ b/dom/ipc/TabParent.h
@@ -577,10 +577,6 @@ public:
 
   layout::RenderFrameParent* GetRenderFrame();
 
-  void AudioChannelChangeNotification(nsPIDOMWindowOuter* aWindow,
-                                      AudioChannel aAudioChannel,
-                                      float aVolume,
-                                      bool aMuted);
   bool SetRenderFrame(PRenderFrameParent* aRFParent);
   bool GetRenderFrameInfo(TextureFactoryIdentifier* aTextureFactoryIdentifier,
                           uint64_t* aLayersId);