diff --git a/dom/base/nsGkAtomList.h b/dom/base/nsGkAtomList.h
index de891601f0..19182dfcc6 100644
--- a/dom/base/nsGkAtomList.h
+++ b/dom/base/nsGkAtomList.h
@@ -2332,3 +2332,13 @@ GK_ATOM(onboundary, "onboundary")
 #endif
 
 GK_ATOM(vr_state, "vr-state")
+
+// MSE
+GK_ATOM(onsourceopen, "onsourceopen")
+GK_ATOM(onsourceended, "onsourceended")
+GK_ATOM(onsourceclosed, "onsourceclosed")
+GK_ATOM(onupdatestart, "onupdatestart")
+GK_ATOM(onupdate, "onupdate")
+GK_ATOM(onupdateend, "onupdateend")
+GK_ATOM(onaddsourcebuffer, "onaddsourcebuffer")
+GK_ATOM(onremovesourcebuffer, "onremovesourcebuffer")
diff --git a/dom/media/mediasource/MediaSource.h b/dom/media/mediasource/MediaSource.h
index 6f6790813b..4ed5cb458f 100644
--- a/dom/media/mediasource/MediaSource.h
+++ b/dom/media/mediasource/MediaSource.h
@@ -72,6 +72,11 @@ public:
   static bool IsTypeSupported(const GlobalObject&, const nsAString& aType);
 
   static bool Enabled(JSContext* cx, JSObject* aGlobal);
+
+  IMPL_EVENT_HANDLER(sourceopen);
+  IMPL_EVENT_HANDLER(sourceended);
+  IMPL_EVENT_HANDLER(sourceclosed)
+
   /** End WebIDL Methods. */
 
   NS_DECL_ISUPPORTS_INHERITED
diff --git a/dom/media/mediasource/SourceBuffer.h b/dom/media/mediasource/SourceBuffer.h
index 8cc0ac3988..fe69489c2c 100644
--- a/dom/media/mediasource/SourceBuffer.h
+++ b/dom/media/mediasource/SourceBuffer.h
@@ -180,6 +180,13 @@ public:
   void AbortBufferAppend();
 
   void Remove(double aStart, double aEnd, ErrorResult& aRv);
+
+  IMPL_EVENT_HANDLER(updatestart);
+  IMPL_EVENT_HANDLER(update);
+  IMPL_EVENT_HANDLER(updateend);
+  IMPL_EVENT_HANDLER(error);
+  IMPL_EVENT_HANDLER(abort);
+
   /** End WebIDL Methods. */
 
   NS_DECL_ISUPPORTS_INHERITED
diff --git a/dom/media/mediasource/SourceBufferList.h b/dom/media/mediasource/SourceBufferList.h
index 1d408e0752..a101b78e7a 100644
--- a/dom/media/mediasource/SourceBufferList.h
+++ b/dom/media/mediasource/SourceBufferList.h
@@ -36,6 +36,10 @@ public:
   SourceBuffer* IndexedGetter(uint32_t aIndex, bool& aFound);
 
   uint32_t Length();
+
+  IMPL_EVENT_HANDLER(addsourcebuffer);
+  IMPL_EVENT_HANDLER(removesourcebuffer);
+
   /** End WebIDL methods. */
 
   NS_DECL_ISUPPORTS_INHERITED
diff --git a/dom/webidl/MediaSource.webidl b/dom/webidl/MediaSource.webidl
index 95a7026fe9..63691e090d 100644
--- a/dom/webidl/MediaSource.webidl
+++ b/dom/webidl/MediaSource.webidl
@@ -28,6 +28,9 @@ interface MediaSource : EventTarget {
   readonly attribute MediaSourceReadyState readyState;
   [SetterThrows]
   attribute unrestricted double duration;
+  attribute EventHandler onsourceopen;
+  attribute EventHandler onsourceended;
+  attribute EventHandler onsourceclosed;
   [NewObject, Throws]
   SourceBuffer addSourceBuffer(DOMString type);
   [Throws]
diff --git a/dom/webidl/SourceBuffer.webidl b/dom/webidl/SourceBuffer.webidl
index aaae3e412d..9104d0b69a 100644
--- a/dom/webidl/SourceBuffer.webidl
+++ b/dom/webidl/SourceBuffer.webidl
@@ -31,6 +31,11 @@ interface SourceBuffer : EventTarget {
   attribute double appendWindowStart;
   [SetterThrows]
   attribute unrestricted double appendWindowEnd;
+  attribute EventHandler onupdatestart;
+  attribute EventHandler onupdate;
+  attribute EventHandler onupdateend;
+  attribute EventHandler onerror;
+  attribute EventHandler onabort;
   [Throws]
   void appendBuffer(ArrayBuffer data);
   [Throws]
diff --git a/dom/webidl/SourceBufferList.webidl b/dom/webidl/SourceBufferList.webidl
index badbfd8252..15c302622a 100644
--- a/dom/webidl/SourceBufferList.webidl
+++ b/dom/webidl/SourceBufferList.webidl
@@ -13,5 +13,7 @@
 [Func="mozilla::dom::MediaSource::Enabled"]
 interface SourceBufferList : EventTarget {
   readonly attribute unsigned long length;
+  attribute EventHandler onaddsourcebuffer;
+  attribute EventHandler onremovesourcebuffer;
   getter SourceBuffer (unsigned long index);
 };