--- a/dom/media/eme/MediaKeySystemAccess.cpp
+++ b/dom/media/eme/MediaKeySystemAccess.cpp
@@ -133,17 +133,23 @@ EnsureMinCDMVersion(mozIGeckoMediaPlugin
 {
   nsTArray<nsCString> tags;
   tags.AppendElement(NS_ConvertUTF16toUTF8(aKeySystem));
   bool hasPlugin;
   nsAutoCString versionStr;
   if (NS_FAILED(aGMPService->GetPluginVersionForAPI(NS_LITERAL_CSTRING(GMP_API_DECRYPTOR),
                                                     &tags,
                                                     &hasPlugin,
-                                                    versionStr))) {
+                                                    versionStr)) ||
+      // XXX to be removed later in bug 1147692
+      (aCheckForV6 && !hasPlugin &&
+       NS_FAILED(aGMPService->GetPluginVersionForAPI(NS_LITERAL_CSTRING(GMP_API_DECRYPTOR_COMPAT),
+                                                     &tags,
+                                                     &hasPlugin,
+                                                     versionStr)))) {
     return MediaKeySystemStatus::Error;
   }
 
   if (!hasPlugin) {
     return MediaKeySystemStatus::Cdm_not_installed;
   }
 
   if (aMinCdmVersion == NO_CDM_VERSION) {
@@ -249,25 +255,35 @@ IsPlayableWithGMP(mozIGeckoMediaPluginSe
                                       codecs,
                                       hasAAC,
                                       hasH264,
                                       hasMP3) ||
       hasMP3) {
     return false;
   }
   return (!hasAAC ||
-          !HaveGMPFor(aGMPS,
-                      NS_ConvertUTF16toUTF8(aKeySystem),
-                      NS_LITERAL_CSTRING(GMP_API_DECRYPTOR),
-                      NS_LITERAL_CSTRING("aac"))) &&
+          !(HaveGMPFor(aGMPS,
+                       NS_ConvertUTF16toUTF8(aKeySystem),
+                       NS_LITERAL_CSTRING(GMP_API_DECRYPTOR),
+                       NS_LITERAL_CSTRING("aac")) ||
+            // XXX remove later in bug 1147692
+            HaveGMPFor(aGMPS,
+                       NS_ConvertUTF16toUTF8(aKeySystem),
+                       NS_LITERAL_CSTRING(GMP_API_DECRYPTOR_COMPAT),
+                       NS_LITERAL_CSTRING("aac")))) &&
          (!hasH264 ||
-          HaveGMPFor(aGMPS,
-                     NS_ConvertUTF16toUTF8(aKeySystem),
-                     NS_LITERAL_CSTRING(GMP_API_DECRYPTOR),
-                     NS_LITERAL_CSTRING("h264")));
+          !(HaveGMPFor(aGMPS,
+                       NS_ConvertUTF16toUTF8(aKeySystem),
+                       NS_LITERAL_CSTRING(GMP_API_DECRYPTOR),
+                       NS_LITERAL_CSTRING("h264")) ||
+            // XXX remove later in bug 1147692
+            HaveGMPFor(aGMPS,
+                       NS_ConvertUTF16toUTF8(aKeySystem),
+                       NS_LITERAL_CSTRING(GMP_API_DECRYPTOR_COMPAT),
+                       NS_LITERAL_CSTRING("h264"))));
 #else
   return false;
 #endif
 }
 
 /* static */
 bool
 MediaKeySystemAccess::IsSupported(const nsAString& aKeySystem,

--- a/dom/media/gmp/GMPContentChild.cpp
+++ b/dom/media/gmp/GMPContentChild.cpp
@@ -113,16 +113,21 @@ GMPContentChild::DeallocPGMPVideoEncoder
 bool
 GMPContentChild::RecvPGMPDecryptorConstructor(PGMPDecryptorChild* aActor)
 {
   GMPDecryptorChild* child = static_cast<GMPDecryptorChild*>(aActor);
   GMPDecryptorHost* host = static_cast<GMPDecryptorHost*>(child);
 
   void* session = nullptr;
   GMPErr err = mGMPChild->GetAPI(GMP_API_DECRYPTOR, host, &session);
+  if (err != GMPNoErr && !session) {
+    // XXX to remove in bug 1147692
+    err = mGMPChild->GetAPI(GMP_API_DECRYPTOR_COMPAT, host, &session);
+  }
+
   if (err != GMPNoErr || !session) {
     return false;
   }
 
   child->Init(static_cast<GMPDecryptor*>(session));
 
   return true;
 }

--- a/dom/media/gmp/GMPParent.cpp
+++ b/dom/media/gmp/GMPParent.cpp
@@ -813,17 +813,18 @@ GMPParent::ReadGMPMetaData()
         nsCCharSeparatedTokenizer tagTokens(ts, ':');
         while (tagTokens.hasMoreTokens()) {
           const nsDependentCSubstring tag(tagTokens.nextToken());
           cap->mAPITags.AppendElement(tag);
         }
       }
     }
 
-    if (cap->mAPIName.EqualsLiteral(GMP_API_DECRYPTOR)) {
+    if (cap->mAPIName.EqualsLiteral(GMP_API_DECRYPTOR) ||
+        cap->mAPIName.EqualsLiteral(GMP_API_DECRYPTOR_COMPAT)) {
       mCanDecrypt = true;
 
 #if defined(XP_LINUX) && defined(MOZ_GMP_SANDBOX)
       if (!mozilla::SandboxInfo::Get().CanSandboxMedia()) {
         printf_stderr("GMPParent::ReadGMPMetaData: Plugin \"%s\" is an EME CDM"
                       " but this system can't sandbox it; not loading.\n",
                       mDisplayName.get());
         delete cap;

--- a/dom/media/gmp/GMPServiceParent.cpp
+++ b/dom/media/gmp/GMPServiceParent.cpp
@@ -663,16 +663,23 @@ GeckoMediaPluginServiceParent::SelectPlu
   if (gmpToClone) {
     GMPParent* clone = ClonePlugin(gmpToClone);
     if (!aNodeId.IsEmpty()) {
       clone->SetNodeId(aNodeId);
     }
     return clone;
   }
 
+  if (aAPI.EqualsLiteral(GMP_API_DECRYPTOR)) {
+    // XXX to remove in bug 1147692
+    return SelectPluginForAPI(aNodeId,
+                              NS_LITERAL_CSTRING(GMP_API_DECRYPTOR_COMPAT),
+                              aTags);
+  }
+
   return nullptr;
 }
 
 class CreateGMPParentTask : public nsRunnable {
 public:
   NS_IMETHOD Run() {
     MOZ_ASSERT(NS_IsMainThread());
 #if defined(XP_LINUX) && defined(MOZ_GMP_SANDBOX)

--- a/dom/media/gmp/gmp-api/gmp-decryption.h
+++ b/dom/media/gmp/gmp-api/gmp-decryption.h
@@ -235,16 +235,19 @@ public:
 enum GMPSessionType {
   kGMPTemporySession = 0,
   kGMPPersistentSession = 1,
   kGMPSessionInvalid = 2 // Must always be last.
 };
 
 #define GMP_API_DECRYPTOR "eme-decrypt-v7"
 
+// XXX remove in bug 1147692
+#define GMP_API_DECRYPTOR_COMPAT "eme-decrypt-v6"
+
 // API exposed by plugin library to manage decryption sessions.
 // When the Host requests this by calling GMPGetAPIFunc().
 //
 // API name macro: GMP_API_DECRYPTOR
 // Host API: GMPDecryptorHost
 class GMPDecryptor {
 public: