--- a/dom/html/HTMLMediaElement.cpp
+++ b/dom/html/HTMLMediaElement.cpp
@@ -1580,16 +1580,21 @@ HTMLMediaElement::MozRequestDebugInfo(Er
   RefPtr<Promise> promise = CreateDOMPromise(aRv);
   if (NS_WARN_IF(aRv.Failed())) {
     return nullptr;
   }
 
   nsAutoString result;
   GetMozDebugReaderData(result);
 
+  if (mVideoFrameContainer) {
+    result.AppendPrintf("Compositor dropped frame(including when element's invisible): %u\n",
+                        mVideoFrameContainer->GetDroppedImageCount());
+  }
+
   if (mMediaKeys) {
     nsString EMEInfo;
     GetEMEInfo(EMEInfo);
     result.AppendLiteral("EME Info: ");
     result.Append(EMEInfo);
     result.AppendLiteral("\n");
   }