diff --git a/dom/media/gmp/ChromiumCDMChild.h b/dom/media/gmp/ChromiumCDMChild.h
index a4dc6983f562..cb790b9fda41 100644
--- a/dom/media/gmp/ChromiumCDMChild.h
+++ b/dom/media/gmp/ChromiumCDMChild.h
@@ -20,7 +20,9 @@ class ChromiumCDMChild : public PChromiumCDMChild,
                          public cdm::Host_9,
                          public cdm::Host_10 {
  public:
-  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(ChromiumCDMChild);
+  // Mark AddRef and Release as `final`, as they overload pure virtual
+  // implementations in PChromiumCDMChild.
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(ChromiumCDMChild, final);
 
   explicit ChromiumCDMChild(GMPContentChild* aPlugin);
 
diff --git a/dom/media/gmp/ChromiumCDMParent.h b/dom/media/gmp/ChromiumCDMParent.h
index 89f8115b0acf..bb8f4c3c0d94 100644
--- a/dom/media/gmp/ChromiumCDMParent.h
+++ b/dom/media/gmp/ChromiumCDMParent.h
@@ -36,7 +36,9 @@ class ChromiumCDMParent final : public PChromiumCDMParent,
  public:
   typedef MozPromise<bool, MediaResult, /* IsExclusive = */ true> InitPromise;
 
-  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(ChromiumCDMParent)
+  // Mark AddRef and Release as `final`, as they overload pure virtual
+  // implementations in PChromiumCDMParent.
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(ChromiumCDMParent, final)
 
   ChromiumCDMParent(GMPContentParent* aContentParent, uint32_t aPluginId);
 
diff --git a/dom/media/gmp/GMPContentChild.cpp b/dom/media/gmp/GMPContentChild.cpp
index 7fcebc89f1a7..f1914c05cf66 100644
--- a/dom/media/gmp/GMPContentChild.cpp
+++ b/dom/media/gmp/GMPContentChild.cpp
@@ -61,15 +61,8 @@ bool GMPContentChild::DeallocPGMPVideoEncoderChild(
   return true;
 }
 
-PChromiumCDMChild* GMPContentChild::AllocPChromiumCDMChild() {
-  ChromiumCDMChild* actor = new ChromiumCDMChild(this);
-  actor->AddRef();
-  return actor;
-}
-
-bool GMPContentChild::DeallocPChromiumCDMChild(PChromiumCDMChild* aActor) {
-  static_cast<ChromiumCDMChild*>(aActor)->Release();
-  return true;
+already_AddRefed<PChromiumCDMChild> GMPContentChild::AllocPChromiumCDMChild() {
+  return MakeAndAddRef<ChromiumCDMChild>(this);
 }
 
 mozilla::ipc::IPCResult GMPContentChild::RecvPGMPVideoDecoderConstructor(
diff --git a/dom/media/gmp/GMPContentChild.h b/dom/media/gmp/GMPContentChild.h
index c2ba9b500aa8..07d952a57cdf 100644
--- a/dom/media/gmp/GMPContentChild.h
+++ b/dom/media/gmp/GMPContentChild.h
@@ -35,8 +35,7 @@ class GMPContentChild : public PGMPContentChild, public GMPSharedMem {
   PGMPVideoEncoderChild* AllocPGMPVideoEncoderChild();
   bool DeallocPGMPVideoEncoderChild(PGMPVideoEncoderChild* aActor);
 
-  PChromiumCDMChild* AllocPChromiumCDMChild();
-  bool DeallocPChromiumCDMChild(PChromiumCDMChild* aActor);
+  already_AddRefed<PChromiumCDMChild> AllocPChromiumCDMChild();
 
   void ActorDestroy(ActorDestroyReason aWhy) override;
   void ProcessingError(Result aCode, const char* aReason) override;
diff --git a/dom/media/gmp/GMPContentParent.cpp b/dom/media/gmp/GMPContentParent.cpp
index a26c6600a2b1..2664ae22e2f5 100644
--- a/dom/media/gmp/GMPContentParent.cpp
+++ b/dom/media/gmp/GMPContentParent.cpp
@@ -162,11 +162,11 @@ nsCOMPtr<nsISerialEventTarget> GMPContentParent::GMPEventTarget() {
 
 already_AddRefed<ChromiumCDMParent> GMPContentParent::GetChromiumCDM() {
   GMP_LOG("GMPContentParent::GetChromiumCDM(this=%p)", this);
-  PChromiumCDMParent* actor = SendPChromiumCDMConstructor();
-  if (!actor) {
+
+  RefPtr<ChromiumCDMParent> parent = new ChromiumCDMParent(this, GetPluginId());
+  if (!SendPChromiumCDMConstructor(parent)) {
     return nullptr;
   }
-  RefPtr<ChromiumCDMParent> parent = static_cast<ChromiumCDMParent*>(actor);
 
   // TODO: Remove parent from mChromiumCDMs in ChromiumCDMParent::Destroy().
   mChromiumCDMs.AppendElement(parent);
@@ -209,13 +209,6 @@ nsresult GMPContentParent::GetGMPVideoEncoder(GMPVideoEncoderParent** aGMPVE) {
   return NS_OK;
 }
 
-PChromiumCDMParent* GMPContentParent::AllocPChromiumCDMParent() {
-  GMP_LOG("GMPContentParent::AllocPChromiumCDMParent(this=%p)", this);
-  ChromiumCDMParent* parent = new ChromiumCDMParent(this, GetPluginId());
-  NS_ADDREF(parent);
-  return parent;
-}
-
 PGMPVideoDecoderParent* GMPContentParent::AllocPGMPVideoDecoderParent(
     const uint32_t& aDecryptorId) {
   GMP_LOG("GMPContentParent::AllocPGMPVideoDecoderParent(this=%p)", this);
@@ -224,14 +217,6 @@ PGMPVideoDecoderParent* GMPContentParent::AllocPGMPVideoDecoderParent(
   return vdp;
 }
 
-bool GMPContentParent::DeallocPChromiumCDMParent(PChromiumCDMParent* aActor) {
-  GMP_LOG("GMPContentParent::DeallocPChromiumCDMParent(this=%p, aActor=%p)",
-          this, aActor);
-  ChromiumCDMParent* parent = static_cast<ChromiumCDMParent*>(aActor);
-  NS_RELEASE(parent);
-  return true;
-}
-
 bool GMPContentParent::DeallocPGMPVideoDecoderParent(
     PGMPVideoDecoderParent* aActor) {
   GMP_LOG("GMPContentParent::DeallocPGMPVideoDecoderParent(this=%p, aActor=%p)",
diff --git a/dom/media/gmp/GMPContentParent.h b/dom/media/gmp/GMPContentParent.h
index fe750b81c686..f4e0c9fad58c 100644
--- a/dom/media/gmp/GMPContentParent.h
+++ b/dom/media/gmp/GMPContentParent.h
@@ -76,9 +76,6 @@ class GMPContentParent final : public PGMPContentParent, public GMPSharedMem {
   PGMPVideoEncoderParent* AllocPGMPVideoEncoderParent() override;
   bool DeallocPGMPVideoEncoderParent(PGMPVideoEncoderParent* aActor) override;
 
-  PChromiumCDMParent* AllocPChromiumCDMParent() override;
-  bool DeallocPChromiumCDMParent(PChromiumCDMParent* aActor) override;
-
   void CloseIfUnused();
   // Needed because NewRunnableMethod tried to use the class that the method
   // lives on to store the receiver, but PGMPContentParent isn't refcounted.
diff --git a/dom/media/gmp/PChromiumCDM.ipdl b/dom/media/gmp/PChromiumCDM.ipdl
index 01a2bb86cdc6..f0bb3eef2a88 100644
--- a/dom/media/gmp/PChromiumCDM.ipdl
+++ b/dom/media/gmp/PChromiumCDM.ipdl
@@ -9,7 +9,7 @@ include GMPTypes;
 namespace mozilla {
 namespace gmp {
 
-async protocol PChromiumCDM
+async refcounted protocol PChromiumCDM
 {
   manager PGMPContent;
 child: