--- a/dom/media/gmp/widevine-adapter/WidevineAdapter.cpp
+++ b/dom/media/gmp/widevine-adapter/WidevineAdapter.cpp
@@ -8,24 +8,21 @@
 #include "VideoUtils.h"
 #include "WidevineDecryptor.h"
 #include "WidevineUtils.h"
 #include "WidevineVideoDecoder.h"
 #include "gmp-api/gmp-entrypoints.h"
 #include "gmp-api/gmp-decryption.h"
 #include "gmp-api/gmp-video-codec.h"
 #include "gmp-api/gmp-platform.h"
-#include "mozilla/StaticPtr.h"
 
 static const GMPPlatformAPI* sPlatform = nullptr;
 
 namespace mozilla {
 
-StaticRefPtr<CDMWrapper> sCDMWrapper;
-
 GMPErr GMPGetCurrentTime(GMPTimestamp* aOutTime) {
   return sPlatform->getcurrenttime(aOutTime);
 }
 
 // Call on main thread only.
 GMPErr GMPSetTimerOnMainThread(GMPTask* aTask, int64_t aTimeoutMS) {
   return sPlatform->settimer(aTask, aTimeoutMS);
 }
@@ -86,59 +83,59 @@ WidevineAdapter::GMPInit(const GMPPlatfo
 }
 
 GMPErr
 WidevineAdapter::GMPGetAPI(const char* aAPIName,
                            void* aHostAPI,
                            void** aPluginAPI,
                            uint32_t aDecryptorId)
 {
-  Log("WidevineAdapter::GMPGetAPI(%s, 0x%p, 0x%p) this=0x%p",
-      aAPIName, aHostAPI, aPluginAPI, this);
+  Log("WidevineAdapter::GMPGetAPI(%s, 0x%p, 0x%p, %u) this=0x%p",
+      aAPIName, aHostAPI, aPluginAPI, this, aDecryptorId);
   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!");
+    if (WidevineDecryptor::GetInstance(aDecryptorId)) {
+      // We only support one CDM instance per PGMPDecryptor. Fail!
+      Log("WidevineAdapter::GMPGetAPI() Tried to create more than once CDM per IPDL actor! FAIL!");
       return GMPQuotaExceededErr;
     }
     auto create = reinterpret_cast<decltype(::CreateCdmInstance)*>(
       PR_FindFunctionSymbol(mLib, "CreateCdmInstance"));
     if (!create) {
-      Log("WidevineAdapter::GMPGetAPI(%s, 0x%p, 0x%p) this=0x%p FAILED to find CreateCdmInstance",
-        aAPIName, aHostAPI, aPluginAPI, this);
+      Log("WidevineAdapter::GMPGetAPI(%s, 0x%p, 0x%p, %u) this=0x%p FAILED to find CreateCdmInstance",
+        aAPIName, aHostAPI, aPluginAPI, this, aDecryptorId);
       return GMPGenericErr;
     }
 
     WidevineDecryptor* decryptor = new WidevineDecryptor();
 
     auto cdm = reinterpret_cast<cdm::ContentDecryptionModule*>(
       create(cdm::ContentDecryptionModule::kVersion,
              kEMEKeySystemWidevine.get(),
              kEMEKeySystemWidevine.Length(),
              &GetCdmHost,
              decryptor));
     if (!cdm) {
-      Log("WidevineAdapter::GMPGetAPI(%s, 0x%p, 0x%p) this=0x%p FAILED to create cdm",
-          aAPIName, aHostAPI, aPluginAPI, this);
+      Log("WidevineAdapter::GMPGetAPI(%s, 0x%p, 0x%p, %u) this=0x%p FAILED to create cdm",
+          aAPIName, aHostAPI, aPluginAPI, this, aDecryptorId);
       return GMPGenericErr;
     }
     Log("cdm: 0x%x", cdm);
-    sCDMWrapper = new CDMWrapper(cdm);
-    decryptor->SetCDM(RefPtr<CDMWrapper>(sCDMWrapper));
+    RefPtr<CDMWrapper> wrapper(new CDMWrapper(cdm));
+    decryptor->SetCDM(wrapper, aDecryptorId);
     *aPluginAPI = decryptor;
 
   } else if (!strcmp(aAPIName, GMP_API_VIDEO_DECODER)) {
-    if (!sCDMWrapper) {
-      Log("WidevineAdapter::GMPGetAPI(%s, 0x%p, 0x%p) this=0x%p No cdm for video decoder",
-          aAPIName, aHostAPI, aPluginAPI, this);
+    RefPtr<CDMWrapper> wrapper = WidevineDecryptor::GetInstance(aDecryptorId);
+    if (!wrapper) {
+      Log("WidevineAdapter::GMPGetAPI(%s, 0x%p, 0x%p, %u) this=0x%p No cdm for video decoder",
+          aAPIName, aHostAPI, aPluginAPI, thiss, aDecryptorId);
       return GMPGenericErr;
     }
     *aPluginAPI = new WidevineVideoDecoder(static_cast<GMPVideoHost*>(aHostAPI),
-                                           RefPtr<CDMWrapper>(sCDMWrapper));
-
+                                           wrapper);
   }
   return *aPluginAPI ? GMPNoErr : GMPNotImplementedErr;
 }
 
 void
 WidevineAdapter::GMPShutdown()
 {
   Log("WidevineAdapter::GMPShutdown()");

--- a/dom/media/gmp/widevine-adapter/WidevineDecryptor.cpp
+++ b/dom/media/gmp/widevine-adapter/WidevineDecryptor.cpp
@@ -11,33 +11,48 @@
 #include <mozilla/SizePrintfMacros.h>
 #include <stdarg.h>
 
 using namespace cdm;
 using namespace std;
 
 namespace mozilla {
 
+static map<uint32_t, RefPtr<CDMWrapper>> sDecryptors;
+
+/* static */
+RefPtr<CDMWrapper>
+WidevineDecryptor::GetInstance(uint32_t aInstanceId)
+{
+  auto itr = sDecryptors.find(aInstanceId);
+  if (itr != sDecryptors.end()) {
+    return itr->second;
+  }
+  return nullptr;
+}
+
 
 WidevineDecryptor::WidevineDecryptor()
   : mCallback(nullptr)
 {
   Log("WidevineDecryptor created this=%p", this);
   AddRef(); // Released in DecryptingComplete().
 }
 
 WidevineDecryptor::~WidevineDecryptor()
 {
   Log("WidevineDecryptor destroyed this=%p", this);
 }
 
 void
-WidevineDecryptor::SetCDM(RefPtr<CDMWrapper> aCDM)
+WidevineDecryptor::SetCDM(RefPtr<CDMWrapper> aCDM, uint32_t aInstanceId)
 {
   mCDM = aCDM;
+  mInstanceId = aInstanceId;
+  sDecryptors[mInstanceId] = aCDM;
 }
 
 void
 WidevineDecryptor::Init(GMPDecryptorCallback* aCallback,
                         bool aDistinctiveIdentifierRequired,
                         bool aPersistentStateRequired)
 {
   Log("WidevineDecryptor::Init() this=%p distinctiveId=%d persistentState=%d",
@@ -205,17 +220,22 @@ WidevineDecryptor::Decrypt(GMPBuffer* aB
   }
   mCallback->Decrypted(aBuffer, ToGMPErr(rv));
 }
 
 void
 WidevineDecryptor::DecryptingComplete()
 {
   Log("WidevineDecryptor::DecryptingComplete() this=%p", this);
+  // Drop our references to the CDMWrapper. When any other references
+  // held elsewhere are dropped (for example references held by a
+  // WidevineVideoDecoder, or a runnable), the CDMWrapper destroys
+  // the CDM.
   mCDM = nullptr;
+  sDecryptors.erase(mInstanceId);
   mCallback = nullptr;
   Release();
 }
 
 class WidevineBuffer : public cdm::Buffer {
 public:
   explicit WidevineBuffer(size_t aSize) {
     Log("WidevineBuffer(size=" PRIuSIZE ") created", aSize);

--- a/dom/media/gmp/widevine-adapter/WidevineDecryptor.h
+++ b/dom/media/gmp/widevine-adapter/WidevineDecryptor.h
@@ -19,17 +19,19 @@ class WidevineDecryptor : public GMPDecr
                         , public cdm::Host_8
 {
 public:
 
   NS_INLINE_DECL_THREADSAFE_REFCOUNTING(WidevineDecryptor)
 
   WidevineDecryptor();
 
-  void SetCDM(RefPtr<CDMWrapper> aCDM);
+  void SetCDM(RefPtr<CDMWrapper> aCDM, uint32_t aDecryptorId);
+
+  static RefPtr<CDMWrapper> GetInstance(uint32_t aDecryptorId);
 
   // GMPDecryptor
   void Init(GMPDecryptorCallback* aCallback,
             bool aDistinctiveIdentifierRequired,
             bool aPersistentStateRequired) override;
 
   void CreateSession(uint32_t aCreateSessionToken,
                      uint32_t aPromiseId,
@@ -119,13 +121,14 @@ private:
   ~WidevineDecryptor();
   RefPtr<CDMWrapper> mCDM;
   cdm::ContentDecryptionModule_8* CDM() { return mCDM->GetCDM(); }
 
   GMPDecryptorCallback* mCallback;
   std::map<uint32_t, uint32_t> mPromiseIdToNewSessionTokens;
   bool mDistinctiveIdentifierRequired = false;
   bool mPersistentStateRequired = false;
+  uint32_t mInstanceId = 0;
 };
 
 } // namespace mozilla
 
 #endif // WidevineDecryptor_h_