Bug 1338446 Part 2 - Label FontFaceSet::CheckLoadingFinishedAfterDelay. r=heycam

mDocument is always valid because we get mDocument from the argument of
FontFaceSet's constructor, and FontFaceSet is always created in
nsIDocument's methods.

Delay giving checkTask a name until we dispatch it. No need to name it
twice.

MozReview-Commit-ID: 6nKYRcRqvQ0

--HG--
extra : rebase_source : 5d7be9c1bcf41ce6fae9ba37a4013144c23fa832

layout/style/FontFaceSet.cpp

@@ -104,6 +104,8 @@ FontFaceSet::FontFaceSet(nsPIDOMWindowInner* aWindow, nsIDocument* aDocument)
   , mHasLoadingFontFacesIsDirty(false)
   , mDelayedLoadCheck(false)
 {
+  MOZ_ASSERT(mDocument, "We should get a valid document from the caller!");
+
   nsCOMPtr<nsIGlobalObject> global = do_QueryInterface(aWindow);
 
   // If the pref is not set, don't create the Promise (which the page wouldn't
@@ -1473,9 +1475,9 @@ FontFaceSet::OnFontFaceStatusChanged(FontFace* aFontFace)
     if (!mDelayedLoadCheck) {
       mDelayedLoadCheck = true;
       nsCOMPtr<nsIRunnable> checkTask =
-        NewRunnableMethod("FontFaceSet::CheckLoadingFinishedAfterDelay",
-                          this, &FontFaceSet::CheckLoadingFinishedAfterDelay);
-      NS_DispatchToMainThread(checkTask);
+        NewRunnableMethod(this, &FontFaceSet::CheckLoadingFinishedAfterDelay);
+      mDocument->Dispatch("FontFaceSet::CheckLoadingFinishedAfterDelay",
+                          TaskCategory::Other, checkTask.forget());
     }
   }
 }