--- a/dom/media/fmp4/SharedDecoderManager.cpp
+++ b/dom/media/fmp4/SharedDecoderManager.cpp
@@ -191,18 +191,20 @@ SharedDecoderProxy::Flush()
   return NS_OK;
 }
 
 nsresult
 SharedDecoderProxy::Drain()
 {
   if (mManager->mActiveProxy == this) {
     return mManager->mDecoder->Drain();
+  } else {
+    mCallback->DrainComplete();
+    return NS_OK;
   }
-  return NS_OK;
 }
 
 nsresult
 SharedDecoderProxy::Shutdown()
 {
   mManager->SetIdle(this);
   return NS_OK;
 }