Bug 1731564: Use motivated SpinEventLoopUntil inside layout/*. r=emilio

Depends on D127226

Differential Revision: https://phabricator.services.mozilla.com/D127230

layout/base/nsDocumentViewer.cpp

@@ -1276,7 +1276,8 @@ nsDocumentViewer::PermitUnload(PermitUnloadAction aAction,
         *aPermitUnload = false;
       });
 
-  SpinEventLoopUntil([&]() { return done; });
+  SpinEventLoopUntil("nsDocumentViewer::PermitUnload"_ns,
+                     [&]() { return done; });
 
   mInPermitUnloadPrompt = false;
   return NS_OK;

layout/printing/ipc/RemotePrintJobChild.cpp

@@ -27,7 +27,8 @@ nsresult RemotePrintJobChild::InitializePrint(const nsString& aDocumentTitle,
   // need to spin a nested event loop until initialization completes.
   Unused << SendInitializePrint(aDocumentTitle, aPrintToFile, aStartPage,
                                 aEndPage);
-  mozilla::SpinEventLoopUntil([&]() { return mPrintInitialized; });
+  mozilla::SpinEventLoopUntil("RemotePrintJobChild::InitializePrint"_ns,
+                              [&]() { return mPrintInitialized; });
 
   return mInitializationResult;
 }