Bug 1376363. P2 - call ContainerType() in EnsureTelemetryReported(). r=gerald

MozReview-Commit-ID: 515Q6nXZ7WU

--HG--
extra : rebase_source : a13964ca23cd561db8f95ad2ffbeac5ff2411238
extra : source : 59e7c3d78a9df5b2827cb14a211d59113968f432

dom/media/MediaDecoder.cpp

@@ -639,8 +639,8 @@ MediaDecoder::EnsureTelemetryReported()
     codecs.AppendElement(mInfo->mVideo.GetAsVideoInfo()->mMimeType);
   }
   if (codecs.IsEmpty()) {
-    codecs.AppendElement(nsPrintfCString(
-      "resource; %s", mResource->GetContentType().OriginalString().Data()));
+    codecs.AppendElement(
+      nsPrintfCString("resource; %s", ContainerType().OriginalString().Data()));
   }
   for (const nsCString& codec : codecs) {
     LOG("Telemetry MEDIA_CODEC_USED= '%s'", codec.get());