diff --git a/dom/media/GetUserMediaRequest.cpp b/dom/media/GetUserMediaRequest.cpp
index 3c8589328571..d5760a87299d 100644
--- a/dom/media/GetUserMediaRequest.cpp
+++ b/dom/media/GetUserMediaRequest.cpp
@@ -5,6 +5,7 @@
 #include "GetUserMediaRequest.h"
 
 #include "base/basictypes.h"
+#include "mozilla/dom/MediaDevicesBinding.h"
 #include "mozilla/dom/MediaStreamBinding.h"
 #include "mozilla/dom/GetUserMediaRequestBinding.h"
 #include "nsIScriptGlobalObject.h"
@@ -20,6 +21,19 @@ GetUserMediaRequest::GetUserMediaRequest(
       mOuterWindowID(aInnerWindow->GetOuterWindow()->WindowID()),
       mCallID(aCallID),
       mConstraints(new MediaStreamConstraints(aConstraints)),
+      mType(GetUserMediaRequestType::Getusermedia),
+      mIsSecure(aIsSecure),
+      mIsHandlingUserInput(aIsHandlingUserInput) {}
+
+GetUserMediaRequest::GetUserMediaRequest(
+    nsPIDOMWindowInner* aInnerWindow, const nsAString& aCallID,
+    const AudioOutputOptions& aAudioOutputOptions, bool aIsSecure,
+    bool aIsHandlingUserInput)
+    : mInnerWindowID(aInnerWindow->WindowID()),
+      mOuterWindowID(aInnerWindow->GetOuterWindow()->WindowID()),
+      mCallID(aCallID),
+      mAudioOutputOptions(new AudioOutputOptions(aAudioOutputOptions)),
+      mType(GetUserMediaRequestType::Selectaudiooutput),
       mIsSecure(aIsSecure),
       mIsHandlingUserInput(aIsHandlingUserInput) {}
 
@@ -31,6 +45,7 @@ GetUserMediaRequest::GetUserMediaRequest(nsPIDOMWindowInner* aInnerWindow,
       mOuterWindowID(0),
       mRawID(aRawId),
       mMediaSource(aMediaSource),
+      mType(GetUserMediaRequestType::Recording_device_stopped),
       mIsSecure(false),
       mIsHandlingUserInput(aIsHandlingUserInput) {
   if (aInnerWindow && aInnerWindow->GetOuterWindow()) {
@@ -53,6 +68,8 @@ JSObject* GetUserMediaRequest::WrapObject(JSContext* aCx,
 
 nsISupports* GetUserMediaRequest::GetParentObject() { return nullptr; }
 
+GetUserMediaRequestType GetUserMediaRequest::Type() { return mType; }
+
 void GetUserMediaRequest::GetCallID(nsString& retval) { retval = mCallID; }
 
 void GetUserMediaRequest::GetRawID(nsString& retval) { retval = mRawID; }
@@ -80,4 +97,12 @@ void GetUserMediaRequest::GetConstraints(MediaStreamConstraints& result) {
   }
 }
 
+void GetUserMediaRequest::GetAudioOutputOptions(AudioOutputOptions& result) {
+  MOZ_ASSERT(result.mDeviceId.IsEmpty(),
+             "result should be default initialized");
+  if (mAudioOutputOptions) {
+    result = *mAudioOutputOptions;
+  }
+}
+
 }  // namespace mozilla::dom
diff --git a/dom/media/GetUserMediaRequest.h b/dom/media/GetUserMediaRequest.h
index 79ff770c0068..0b9ab6df9095 100644
--- a/dom/media/GetUserMediaRequest.h
+++ b/dom/media/GetUserMediaRequest.h
@@ -19,15 +19,22 @@ class nsPIDOMWindowInner;
 namespace mozilla {
 namespace dom {
 
+struct AudioOutputOptions;
 struct MediaStreamConstraints;
+enum class GetUserMediaRequestType : uint8_t;
 
 class GetUserMediaRequest : public nsISupports, public nsWrapperCache {
  public:
-  // For "getUserMedia:request"
+  // For getUserMedia "getUserMedia:request"
   GetUserMediaRequest(nsPIDOMWindowInner* aInnerWindow,
                       const nsAString& aCallID,
                       const MediaStreamConstraints& aConstraints,
                       bool aIsSecure, bool aIsHandlingUserInput);
+  // For selectAudioOutput "getUserMedia:request"
+  GetUserMediaRequest(nsPIDOMWindowInner* aInnerWindow,
+                      const nsAString& aCallID,
+                      const AudioOutputOptions& aAudioOutputOptions,
+                      bool aIsSecure, bool aIsHandlingUserInput);
   // For "recording-device-stopped"
   GetUserMediaRequest(nsPIDOMWindowInner* aInnerWindow, const nsAString& aRawId,
                       const nsAString& aMediaSource, bool aIsHandlingUserInput);
@@ -39,6 +46,7 @@ class GetUserMediaRequest : public nsISupports, public nsWrapperCache {
                        JS::Handle<JSObject*> aGivenProto) override;
   nsISupports* GetParentObject();
 
+  GetUserMediaRequestType Type();
   uint64_t WindowID();
   uint64_t InnerWindowID();
   bool IsSecure();
@@ -47,6 +55,7 @@ class GetUserMediaRequest : public nsISupports, public nsWrapperCache {
   void GetRawID(nsString& retval);
   void GetMediaSource(nsString& retval);
   void GetConstraints(MediaStreamConstraints& result);
+  void GetAudioOutputOptions(AudioOutputOptions& result);
 
  private:
   virtual ~GetUserMediaRequest() = default;
@@ -56,6 +65,8 @@ class GetUserMediaRequest : public nsISupports, public nsWrapperCache {
   const nsString mRawID;
   const nsString mMediaSource;
   UniquePtr<MediaStreamConstraints> mConstraints;
+  UniquePtr<AudioOutputOptions> mAudioOutputOptions;
+  GetUserMediaRequestType mType;
   bool mIsSecure;
   bool mIsHandlingUserInput;
 };
diff --git a/dom/webidl/GetUserMediaRequest.webidl b/dom/webidl/GetUserMediaRequest.webidl
index 6762f571a6c1..01855743d11f 100644
--- a/dom/webidl/GetUserMediaRequest.webidl
+++ b/dom/webidl/GetUserMediaRequest.webidl
@@ -6,22 +6,32 @@
  * This is an internal IDL file
  */
 
-// for gUM request start (getUserMedia:request) notification,
-// rawID and mediaSource won't be set.
-// for gUM request stop (recording-device-stopped) notification due to page reload,
-// only windowID will be set.
-// for gUM request stop (recording-device-stopped) notification due to track stop,
-// only windowID, rawID and mediaSource will be set
+// For gUM request start (getUserMedia:request) notification,
+// rawID, mediaSource and audioOutputOptions won't be set.
+// For selectAudioOutput request start (getUserMedia:request) notification,
+// rawID, mediaSource and constraints won't be set.
+// For gUM request stop (recording-device-stopped) notification due to page
+// reload, only windowID will be set.
+// For gUM request stop (recording-device-stopped) notification due to track
+// stop, only type, windowID, rawID and mediaSource will be set
+
+enum GetUserMediaRequestType {
+    "getusermedia",
+    "selectaudiooutput",
+    "recording-device-stopped"
+};
 
 [NoInterfaceObject,
  Exposed=Window]
 interface GetUserMediaRequest {
+  readonly attribute GetUserMediaRequestType type;
   readonly attribute unsigned long long windowID;
   readonly attribute unsigned long long innerWindowID;
   readonly attribute DOMString callID;
   readonly attribute DOMString rawID;
   readonly attribute DOMString mediaSource;
   MediaStreamConstraints getConstraints();
+  AudioOutputOptions getAudioOutputOptions();
   readonly attribute boolean isSecure;
   readonly attribute boolean isHandlingUserInput;
 };