--- a/dom/media/eme/CDMProxy.h
+++ b/dom/media/eme/CDMProxy.h
@@ -12,16 +12,17 @@
 
 #include "mozilla/dom/MediaKeyMessageEvent.h"
 #include "mozilla/dom/MediaKeys.h"
 
 #include "nsIThread.h"
 
 namespace mozilla {
 class MediaRawData;
+class ChromiumCDMProxy;
 
 enum DecryptStatus {
   Ok = 0,
   GenericErr = 1,
   NoKeyErr = 2,
   AbortedErr = 3,
 };
 
@@ -218,16 +219,18 @@ public:
                                      nsTArray<nsCString>& aSessionIds) = 0;
 
 #ifdef DEBUG
   virtual bool IsOnOwnerThread() = 0;
 #endif
 
   virtual uint32_t GetDecryptorId() { return 0; }
 
+  virtual ChromiumCDMProxy* AsChromiumCDMProxy() { return nullptr; }
+
 protected:
   virtual ~CDMProxy() {}
 
   // Helper to enforce that a raw pointer is only accessed on the main thread.
   template<class Type>
   class MainThreadOnlyRawPtr {
   public:
     explicit MainThreadOnlyRawPtr(Type* aPtr)

--- a/dom/media/gmp/ChromiumCDMProxy.h
+++ b/dom/media/gmp/ChromiumCDMProxy.h
@@ -102,16 +102,18 @@ public:
 
   void GetSessionIdsForKeyId(const nsTArray<uint8_t>& aKeyId,
                              nsTArray<nsCString>& aSessionIds) override;
 
 #ifdef DEBUG
   bool IsOnOwnerThread() override;
 #endif
 
+  ChromiumCDMProxy* AsChromiumCDMProxy() override { return this; }
+
 private:
   void OnCDMCreated(uint32_t aPromiseId);
 
   ~ChromiumCDMProxy();
 
   GMPCrashHelper* mCrashHelper;
 
   RefPtr<gmp::ChromiumCDMParent> mCDM;