diff --git a/dom/ipc/ContentChild.cpp b/dom/ipc/ContentChild.cpp
index ce41860fc3da..3ac1cb51e5c7 100644
--- a/dom/ipc/ContentChild.cpp
+++ b/dom/ipc/ContentChild.cpp
@@ -194,7 +194,6 @@
 #include "mozilla/widget/PuppetBidiKeyboard.h"
 #include "mozilla/RemoteSpellCheckEngineChild.h"
 #include "GMPServiceChild.h"
-#include "GMPDecoderModule.h"
 #include "gfxPlatform.h"
 #include "nscore.h" // for NS_FREE_PERMANENT_DATA
 #include "VRManagerChild.h"
@@ -1705,14 +1704,6 @@ ContentChild::RecvNotifyPresentationReceiverCleanUp(const nsString& aSessionId)
   return true;
 }
 
-bool
-ContentChild::RecvNotifyGMPsChanged()
-{
-  GMPDecoderModule::UpdateUsableCodecs();
-  MOZ_ASSERT(NS_IsMainThread());
-  return true;
-}
-
 bool
 ContentChild::RecvNotifyEmptyHTTPCache()
 {
diff --git a/dom/ipc/ContentChild.h b/dom/ipc/ContentChild.h
index c39d6dc94a60..36b3667c51e7 100644
--- a/dom/ipc/ContentChild.h
+++ b/dom/ipc/ContentChild.h
@@ -360,8 +360,6 @@ public:
   virtual bool
   RecvNotifyPresentationReceiverCleanUp(const nsString& aSessionId) override;
 
-  virtual bool RecvNotifyGMPsChanged() override;
-
   virtual bool RecvNotifyEmptyHTTPCache() override;
 
   virtual PSpeechSynthesisChild* AllocPSpeechSynthesisChild() override;
diff --git a/dom/ipc/ContentParent.cpp b/dom/ipc/ContentParent.cpp
index cbbb14ba0e16..ff721c4230e7 100644
--- a/dom/ipc/ContentParent.cpp
+++ b/dom/ipc/ContentParent.cpp
@@ -561,7 +561,6 @@ static const char* sObserverTopics[] = {
   "profiler-subprocess-gather",
   "profiler-subprocess",
 #endif
-  "gmp-changed",
   "cacheservice:empty-cache",
 };
 
@@ -2846,9 +2845,6 @@ ContentParent::Observe(nsISupports* aSubject,
     Unused << SendPauseProfiler(false);
   }
 #endif
-  else if (!strcmp(aTopic, "gmp-changed")) {
-    Unused << SendNotifyGMPsChanged();
-  }
   else if (!strcmp(aTopic, "cacheservice:empty-cache")) {
     Unused << SendNotifyEmptyHTTPCache();
   }
diff --git a/dom/ipc/PContent.ipdl b/dom/ipc/PContent.ipdl
index 00e8b57b3cfc..d5865c2591b6 100644
--- a/dom/ipc/PContent.ipdl
+++ b/dom/ipc/PContent.ipdl
@@ -628,11 +628,6 @@ child:
      */
     async NotifyPresentationReceiverCleanUp(nsString aSessionId);
 
-    /**
-     * Notify the child that the Gecko Media Plugins installed changed.
-     */
-    async NotifyGMPsChanged();
-
     /**
      * Notify the child that cache is emptied.
      */