--- a/dom/media/gmp/GMPChild.cpp
+++ b/dom/media/gmp/GMPChild.cpp
@@ -272,22 +272,25 @@ GMPChild::RecvSetNodeId(const nsCString&
   // Store the per origin salt for the node id. Note: we do this in a
   // separate message than RecvStartPlugin() so that the string is not
   // sitting in a string on the IPC code's call stack.
   mNodeId = aNodeId;
   return true;
 }
 
 GMPErr
-GMPChild::GetAPI(const char* aAPIName, void* aHostAPI, void** aPluginAPI)
+GMPChild::GetAPI(const char* aAPIName,
+                 void* aHostAPI,
+                 void** aPluginAPI,
+                 uint32_t aDecryptorId)
 {
   if (!mGMPLoader) {
     return GMPGenericErr;
   }
-  return mGMPLoader->GetAPI(aAPIName, aHostAPI, aPluginAPI);
+  return mGMPLoader->GetAPI(aAPIName, aHostAPI, aPluginAPI, aDecryptorId);
 }
 
 bool
 GMPChild::RecvPreloadLibs(const nsCString& aLibs)
 {
 #ifdef XP_WIN
   // Pre-load DLLs that need to be used by the EME plugin but that can't be
   // loaded after the sandbox has started

--- a/dom/media/gmp/GMPChild.h
+++ b/dom/media/gmp/GMPChild.h
@@ -71,17 +71,17 @@ private:
 
   bool RecvCrashPluginNow() override;
   bool RecvBeginAsyncShutdown() override;
   bool RecvCloseActive() override;
 
   void ActorDestroy(ActorDestroyReason aWhy) override;
   void ProcessingError(Result aCode, const char* aReason) override;
 
-  GMPErr GetAPI(const char* aAPIName, void* aHostAPI, void** aPluginAPI);
+  GMPErr GetAPI(const char* aAPIName, void* aHostAPI, void** aPluginAPI, uint32_t aDecryptorId = 0);
 
   nsTArray<UniquePtr<GMPContentChild>> mGMPContentChildren;
 
   GMPAsyncShutdown* mAsyncShutdown;
   RefPtr<GMPTimerChild> mTimerChild;
   RefPtr<GMPStorageChild> mStorage;
 
   MessageLoop* mGMPMessageLoop;

--- a/dom/media/gmp/GMPContentChild.cpp
+++ b/dom/media/gmp/GMPContentChild.cpp
@@ -201,17 +201,17 @@ private:
 
 bool
 GMPContentChild::RecvPGMPDecryptorConstructor(PGMPDecryptorChild* aActor)
 {
   GMPDecryptorChild* child = static_cast<GMPDecryptorChild*>(aActor);
   GMPDecryptorHost* host = static_cast<GMPDecryptorHost*>(child);
 
   void* ptr = nullptr;
-  GMPErr err = mGMPChild->GetAPI(GMP_API_DECRYPTOR, host, &ptr);
+  GMPErr err = mGMPChild->GetAPI(GMP_API_DECRYPTOR, host, &ptr, aActor->Id());
   GMPDecryptor* decryptor = nullptr;
   if (GMP_SUCCEEDED(err) && ptr) {
     decryptor = static_cast<GMPDecryptor*>(ptr);
   } else if (err != GMPNoErr) {
     // We Adapt the previous GMPDecryptor version to the current, so that
     // Gecko thinks it's only talking to the current version. v7 differs
     // from v9 in its Init() function arguments, and v9 has extra enumeration
     // members at the end of the key status enumerations.
@@ -245,17 +245,17 @@ GMPContentChild::RecvPGMPAudioDecoderCon
 
 bool
 GMPContentChild::RecvPGMPVideoDecoderConstructor(PGMPVideoDecoderChild* aActor,
                                                  const uint32_t& aDecryptorId)
 {
   auto vdc = static_cast<GMPVideoDecoderChild*>(aActor);
 
   void* vd = nullptr;
-  GMPErr err = mGMPChild->GetAPI(GMP_API_VIDEO_DECODER, &vdc->Host(), &vd);
+  GMPErr err = mGMPChild->GetAPI(GMP_API_VIDEO_DECODER, &vdc->Host(), &vd, aDecryptorId);
   if (err != GMPNoErr || !vd) {
     NS_WARNING("GMPGetAPI call failed trying to construct decoder.");
     return false;
   }
 
   vdc->Init(static_cast<GMPVideoDecoder*>(vd));
 
   return true;

--- a/dom/media/gmp/GMPLoader.cpp
+++ b/dom/media/gmp/GMPLoader.cpp
@@ -34,17 +34,18 @@ public:
             uint32_t aUTF8LibPathLen,
             char* aOriginSalt,
             uint32_t aOriginSaltLen,
             const GMPPlatformAPI* aPlatformAPI,
             GMPAdapter* aAdapter) override;
 
   GMPErr GetAPI(const char* aAPIName,
                 void* aHostAPI,
-                void** aPluginAPI) override;
+                void** aPluginAPI,
+                uint32_t aDecryptorId) override;
 
   void Shutdown() override;
 
 #if defined(XP_MACOSX) && defined(MOZ_GMP_SANDBOX)
   void SetSandboxInfo(MacSandboxInfo* aSandboxInfo) override;
 #endif
 
 private:
@@ -75,17 +76,20 @@ public:
     }
     GMPInitFunc initFunc = reinterpret_cast<GMPInitFunc>(PR_FindFunctionSymbol(mLib, "GMPInit"));
     if (!initFunc) {
       return GMPNotImplementedErr;
     }
     return initFunc(aPlatformAPI);
   }
 
-  GMPErr GMPGetAPI(const char* aAPIName, void* aHostAPI, void** aPluginAPI) override
+  GMPErr GMPGetAPI(const char* aAPIName,
+                   void* aHostAPI,
+                   void** aPluginAPI,
+                   uint32_t aDecryptorId) override
   {
     if (!mLib) {
       return GMPGenericErr;
     }
     GMPGetAPIFunc getapiFunc = reinterpret_cast<GMPGetAPIFunc>(PR_FindFunctionSymbol(mLib, "GMPGetAPI"));
     if (!getapiFunc) {
       return GMPNotImplementedErr;
     }
@@ -185,19 +189,20 @@ GMPLoaderImpl::Load(const char* aUTF8Lib
   mAdapter->GMPSetNodeId(nodeId.c_str(), nodeId.size());
 
   return true;
 }
 
 GMPErr
 GMPLoaderImpl::GetAPI(const char* aAPIName,
                       void* aHostAPI,
-                      void** aPluginAPI)
+                      void** aPluginAPI,
+                      uint32_t aDecryptorId)
 {
-  return mAdapter->GMPGetAPI(aAPIName, aHostAPI, aPluginAPI);
+  return mAdapter->GMPGetAPI(aAPIName, aHostAPI, aPluginAPI, aDecryptorId);
 }
 
 void
 GMPLoaderImpl::Shutdown()
 {
   if (mAdapter) {
     mAdapter->GMPShutdown();
   }

--- a/dom/media/gmp/GMPLoader.h
+++ b/dom/media/gmp/GMPLoader.h
@@ -37,17 +37,20 @@ public:
   virtual ~GMPAdapter() {}
   // Sets the adapted to plugin library module.
   // Note: the GMPAdapter is responsible for calling PR_UnloadLibrary on aLib
   // when it's finished with it.
   virtual void SetAdaptee(PRLibrary* aLib) = 0;
 
   // These are called in place of the corresponding GMP API functions.
   virtual GMPErr GMPInit(const GMPPlatformAPI* aPlatformAPI) = 0;
-  virtual GMPErr GMPGetAPI(const char* aAPIName, void* aHostAPI, void** aPluginAPI) = 0;
+  virtual GMPErr GMPGetAPI(const char* aAPIName,
+                           void* aHostAPI,
+                           void** aPluginAPI,
+                           uint32_t aDecryptorId) = 0;
   virtual void GMPShutdown() = 0;
   virtual void GMPSetNodeId(const char* aNodeId, uint32_t aLength) = 0;
 };
 
 // Encapsulates generating the device-bound node id, activating the sandbox,
 // loading the GMP, and passing the node id to the GMP (in that order).
 //
 // In Desktop Gecko, the implementation of this lives in plugin-container,
@@ -78,17 +81,20 @@ public:
   virtual bool Load(const char* aUTF8LibPath,
                     uint32_t aLibPathLen,
                     char* aOriginSalt,
                     uint32_t aOriginSaltLen,
                     const GMPPlatformAPI* aPlatformAPI,
                     GMPAdapter* aAdapter = nullptr) = 0;
 
   // Retrieves an interface pointer from the GMP.
-  virtual GMPErr GetAPI(const char* aAPIName, void* aHostAPI, void** aPluginAPI) = 0;
+  virtual GMPErr GetAPI(const char* aAPIName,
+                        void* aHostAPI,
+                        void** aPluginAPI,
+                        uint32_t aDecryptorId) = 0;
 
   // Calls the GMPShutdown function exported by the GMP lib, and unloads the
   // plugin library.
   virtual void Shutdown() = 0;
 
 #if defined(XP_MACOSX) && defined(MOZ_GMP_SANDBOX)
   // On OS X we need to set Mac-specific sandbox info just before we start the
   // sandbox, which we don't yet know when the GMPLoader and SandboxStarter

--- a/dom/media/gmp/widevine-adapter/WidevineAdapter.cpp
+++ b/dom/media/gmp/widevine-adapter/WidevineAdapter.cpp
@@ -83,17 +83,18 @@ WidevineAdapter::GMPInit(const GMPPlatfo
   init();
 
   return GMPNoErr;
 }
 
 GMPErr
 WidevineAdapter::GMPGetAPI(const char* aAPIName,
                            void* aHostAPI,
-                           void** aPluginAPI)
+                           void** aPluginAPI,
+                           uint32_t aDecryptorId)
 {
   Log("WidevineAdapter::GMPGetAPI(%s, 0x%p, 0x%p) this=0x%p",
       aAPIName, aHostAPI, aPluginAPI, this);
   if (!strcmp(aAPIName, GMP_API_DECRYPTOR)) {
     if (sCDMWrapper) {
       // We only support one CDM instance per GMP process. Fail!
       Log("WidevineAdapter::GMPGetAPI() Tried to create more than once CDM per process! FAIL!");
       return GMPQuotaExceededErr;

--- a/dom/media/gmp/widevine-adapter/WidevineAdapter.h
+++ b/dom/media/gmp/widevine-adapter/WidevineAdapter.h
@@ -16,17 +16,20 @@ namespace mozilla {
 
 class WidevineAdapter : public gmp::GMPAdapter {
 public:
 
   void SetAdaptee(PRLibrary* aLib) override;
 
   // These are called in place of the corresponding GMP API functions.
   GMPErr GMPInit(const GMPPlatformAPI* aPlatformAPI) override;
-  GMPErr GMPGetAPI(const char* aAPIName, void* aHostAPI, void** aPluginAPI) override;
+  GMPErr GMPGetAPI(const char* aAPIName,
+                   void* aHostAPI,
+                   void** aPluginAPI,
+                   uint32_t aDecryptorId) override;
   void GMPShutdown() override;
   void GMPSetNodeId(const char* aNodeId, uint32_t aLength) override;
 
   static bool Supports(int32_t aModuleVersion,
                        int32_t aInterfaceVersion,
                        int32_t aHostVersion);
 
 private: