diff --git a/dom/media/gmp/GMPAudioDecoderParent.cpp b/dom/media/gmp/GMPAudioDecoderParent.cpp
index 2b801b45433..72facefc3fb 100644
--- a/dom/media/gmp/GMPAudioDecoderParent.cpp
+++ b/dom/media/gmp/GMPAudioDecoderParent.cpp
@@ -28,6 +28,8 @@ GMPAudioDecoderParent::GMPAudioDecoderParent(GMPContentParent* aPlugin)
   : mIsOpen(false)
   , mShuttingDown(false)
   , mActorDestroyed(false)
+  , mIsAwaitingResetComplete(false)
+  , mIsAwaitingDrainComplete(false)
   , mPlugin(aPlugin)
   , mCallback(nullptr)
 {
@@ -109,6 +111,8 @@ GMPAudioDecoderParent::Reset()
     return NS_ERROR_FAILURE;
   }
 
+  mIsAwaitingResetComplete = true;
+
   // Async IPC, we don't have access to a return value.
   return NS_OK;
 }
@@ -127,6 +131,8 @@ GMPAudioDecoderParent::Drain()
     return NS_ERROR_FAILURE;
   }
 
+  mIsAwaitingDrainComplete = true;
+
   // Async IPC, we don't have access to a return value.
   return NS_OK;
 }
@@ -138,6 +144,11 @@ GMPAudioDecoderParent::Close()
   LOGD(("%s: %p", __FUNCTION__, this));
   MOZ_ASSERT(!mPlugin || mPlugin->GMPThread() == NS_GetCurrentThread());
 
+  // Ensure if we've received a Close while waiting for a ResetComplete
+  // or DrainComplete notification, we'll unblock the caller before processing
+  // the close. This seems unlikely to happen, but better to be careful.
+  UnblockResetAndDrain();
+
   // Consumer is done with us; we can shut down.  No more callbacks should
   // be made to mCallback.  Note: do this before Shutdown()!
   mCallback = nullptr;
@@ -163,6 +174,11 @@ GMPAudioDecoderParent::Shutdown()
   }
   mShuttingDown = true;
 
+  // Ensure if we've received a shutdown while waiting for a ResetComplete
+  // or DrainComplete notification, we'll unblock the caller before processing
+  // the shutdown.
+  UnblockResetAndDrain();
+
   // Notify client we're gone!  Won't occur after Close()
   if (mCallback) {
     mCallback->Terminated();
@@ -183,6 +199,12 @@ GMPAudioDecoderParent::ActorDestroy(ActorDestroyReason aWhy)
 {
   mIsOpen = false;
   mActorDestroyed = true;
+
+  // Ensure if we've received a destroy while waiting for a ResetComplete
+  // or DrainComplete notification, we'll unblock the caller before processing
+  // the error.
+  UnblockResetAndDrain();
+
   if (mCallback) {
     // May call Close() (and Shutdown()) immediately or with a delay
     mCallback->Terminated();
@@ -230,6 +252,11 @@ GMPAudioDecoderParent::RecvDrainComplete()
     return false;
   }
 
+  if (!mIsAwaitingDrainComplete) {
+    return true;
+  }
+  mIsAwaitingDrainComplete = false;
+
   // Ignore any return code. It is OK for this to fail without killing the process.
   mCallback->DrainComplete();
 
@@ -243,6 +270,11 @@ GMPAudioDecoderParent::RecvResetComplete()
     return false;
   }
 
+  if (!mIsAwaitingResetComplete) {
+    return true;
+  }
+  mIsAwaitingResetComplete = false;
+
   // Ignore any return code. It is OK for this to fail without killing the process.
   mCallback->ResetComplete();
 
@@ -256,6 +288,11 @@ GMPAudioDecoderParent::RecvError(const GMPErr& aError)
     return false;
   }
 
+  // Ensure if we've received an error while waiting for a ResetComplete
+  // or DrainComplete notification, we'll unblock the caller before processing
+  // the error.
+  UnblockResetAndDrain();
+
   // Ignore any return code. It is OK for this to fail without killing the process.
   mCallback->Error(aError);
 
@@ -281,5 +318,23 @@ GMPAudioDecoderParent::Recv__delete__()
   return true;
 }
 
+void
+GMPAudioDecoderParent::UnblockResetAndDrain()
+{
+  if (!mCallback) {
+    MOZ_ASSERT(!mIsAwaitingResetComplete);
+    MOZ_ASSERT(!mIsAwaitingDrainComplete);
+    return;
+  }
+  if (mIsAwaitingResetComplete) {
+    mIsAwaitingResetComplete = false;
+    mCallback->ResetComplete();
+  }
+  if (mIsAwaitingDrainComplete) {
+    mIsAwaitingDrainComplete = false;
+    mCallback->DrainComplete();
+  }
+}
+
 } // namespace gmp
 } // namespace mozilla
diff --git a/dom/media/gmp/GMPAudioDecoderParent.h b/dom/media/gmp/GMPAudioDecoderParent.h
index 8379f6f89fe..cb19021f5d7 100644
--- a/dom/media/gmp/GMPAudioDecoderParent.h
+++ b/dom/media/gmp/GMPAudioDecoderParent.h
@@ -53,9 +53,13 @@ private:
   virtual bool RecvShutdown() override;
   virtual bool Recv__delete__() override;
 
+  void UnblockResetAndDrain();
+
   bool mIsOpen;
   bool mShuttingDown;
   bool mActorDestroyed;
+  bool mIsAwaitingResetComplete;
+  bool mIsAwaitingDrainComplete;
   nsRefPtr<GMPContentParent> mPlugin;
   GMPAudioDecoderCallbackProxy* mCallback;
 };
diff --git a/dom/media/gmp/GMPVideoDecoderParent.cpp b/dom/media/gmp/GMPVideoDecoderParent.cpp
index 8491a67d15d..68e633f8701 100644
--- a/dom/media/gmp/GMPVideoDecoderParent.cpp
+++ b/dom/media/gmp/GMPVideoDecoderParent.cpp
@@ -43,6 +43,8 @@ GMPVideoDecoderParent::GMPVideoDecoderParent(GMPContentParent* aPlugin)
   , mIsOpen(false)
   , mShuttingDown(false)
   , mActorDestroyed(false)
+  , mIsAwaitingResetComplete(false)
+  , mIsAwaitingDrainComplete(false)
   , mPlugin(aPlugin)
   , mCallback(nullptr)
   , mVideoHost(this)
@@ -67,6 +69,12 @@ GMPVideoDecoderParent::Close()
 {
   LOGD(("%s: %p", __FUNCTION__, this));
   MOZ_ASSERT(!mPlugin || mPlugin->GMPThread() == NS_GetCurrentThread());
+
+  // Ensure if we've received a Close while waiting for a ResetComplete
+  // or DrainComplete notification, we'll unblock the caller before processing
+  // the close. This seems unlikely to happen, but better to be careful.
+  UnblockResetAndDrain();
+
   // Consumer is done with us; we can shut down.  No more callbacks should
   // be made to mCallback.  Note: do this before Shutdown()!
   mCallback = nullptr;
@@ -161,6 +169,8 @@ GMPVideoDecoderParent::Reset()
     return NS_ERROR_FAILURE;
   }
 
+  mIsAwaitingResetComplete = true;
+
   // Async IPC, we don't have access to a return value.
   return NS_OK;
 }
@@ -179,6 +189,8 @@ GMPVideoDecoderParent::Drain()
     return NS_ERROR_FAILURE;
   }
 
+  mIsAwaitingDrainComplete = true;
+
   // Async IPC, we don't have access to a return value.
   return NS_OK;
 }
@@ -207,6 +219,11 @@ GMPVideoDecoderParent::Shutdown()
   }
   mShuttingDown = true;
 
+  // Ensure if we've received a shutdown while waiting for a ResetComplete
+  // or DrainComplete notification, we'll unblock the caller before processing
+  // the shutdown.
+  UnblockResetAndDrain();
+
   // Notify client we're gone!  Won't occur after Close()
   if (mCallback) {
     mCallback->Terminated();
@@ -229,6 +246,11 @@ GMPVideoDecoderParent::ActorDestroy(ActorDestroyReason aWhy)
   mActorDestroyed = true;
   mVideoHost.DoneWithAPI();
 
+  // Ensure if we've received a destroy while waiting for a ResetComplete
+  // or DrainComplete notification, we'll unblock the caller before processing
+  // the error.
+  UnblockResetAndDrain();
+
   if (mCallback) {
     // May call Close() (and Shutdown()) immediately or with a delay
     mCallback->Terminated();
@@ -307,6 +329,11 @@ GMPVideoDecoderParent::RecvDrainComplete()
     return false;
   }
 
+  if (!mIsAwaitingDrainComplete) {
+    return true;
+  }
+  mIsAwaitingDrainComplete = false;
+
   // Ignore any return code. It is OK for this to fail without killing the process.
   mCallback->DrainComplete();
 
@@ -320,6 +347,11 @@ GMPVideoDecoderParent::RecvResetComplete()
     return false;
   }
 
+  if (!mIsAwaitingResetComplete) {
+    return true;
+  }
+  mIsAwaitingResetComplete = false;
+
   // Ignore any return code. It is OK for this to fail without killing the process.
   mCallback->ResetComplete();
 
@@ -333,6 +365,11 @@ GMPVideoDecoderParent::RecvError(const GMPErr& aError)
     return false;
   }
 
+  // Ensure if we've received an error while waiting for a ResetComplete
+  // or DrainComplete notification, we'll unblock the caller before processing
+  // the error.
+  UnblockResetAndDrain();
+
   // Ignore any return code. It is OK for this to fail without killing the process.
   mCallback->Error(aError);
 
@@ -387,5 +424,23 @@ GMPVideoDecoderParent::Recv__delete__()
   return true;
 }
 
+void
+GMPVideoDecoderParent::UnblockResetAndDrain()
+{
+  if (!mCallback) {
+    MOZ_ASSERT(!mIsAwaitingResetComplete);
+    MOZ_ASSERT(!mIsAwaitingDrainComplete);
+    return;
+  }
+  if (mIsAwaitingResetComplete) {
+    mIsAwaitingResetComplete = false;
+    mCallback->ResetComplete();
+  }
+  if (mIsAwaitingDrainComplete) {
+    mIsAwaitingDrainComplete = false;
+    mCallback->DrainComplete();
+  }
+}
+
 } // namespace gmp
 } // namespace mozilla
diff --git a/dom/media/gmp/GMPVideoDecoderParent.h b/dom/media/gmp/GMPVideoDecoderParent.h
index 9b54403146f..1f477ed4176 100644
--- a/dom/media/gmp/GMPVideoDecoderParent.h
+++ b/dom/media/gmp/GMPVideoDecoderParent.h
@@ -79,9 +79,13 @@ private:
                                Shmem* aMem) override;
   virtual bool Recv__delete__() override;
 
+  void UnblockResetAndDrain();
+
   bool mIsOpen;
   bool mShuttingDown;
   bool mActorDestroyed;
+  bool mIsAwaitingResetComplete;
+  bool mIsAwaitingDrainComplete;
   nsRefPtr<GMPContentParent> mPlugin;
   GMPVideoDecoderCallbackProxy* mCallback;
   GMPVideoHostImpl mVideoHost;