Bug 1731564: Use motivated SpinEventLoopUntil inside widget/*. r=smaug

Depends on D127235

Differential Revision: https://phabricator.services.mozilla.com/D127236

widget/windows/nsDataObj.cpp

@@ -160,7 +160,8 @@ NS_IMETHODIMP nsDataObj::CStream::OnStopRequest(nsIRequest* aRequest,
 // and cancel the operation.
 nsresult nsDataObj::CStream::WaitForCompletion() {
   // We are guaranteed OnStopRequest will get called, so this should be ok.
-  SpinEventLoopUntil([&]() { return mChannelRead; });
+  SpinEventLoopUntil("widget:nsDataObj::CStream::WaitForCompletion"_ns,
+                     [&]() { return mChannelRead; });
 
   if (!mChannelData.Length()) mChannelResult = NS_ERROR_FAILURE;