Bug 937688 - Refactor some code to extract a TabChild::GetDocument method. r=botond

dom/ipc/TabChild.cpp

@@ -371,9 +371,7 @@ TabChild::Observe(nsISupports *aSubject,
   } else if (!strcmp(aTopic, BEFORE_FIRST_PAINT)) {
     if (IsAsyncPanZoomEnabled()) {
       nsCOMPtr<nsIDocument> subject(do_QueryInterface(aSubject));
-      nsCOMPtr<nsIDOMDocument> domDoc;
-      mWebNav->GetDocument(getter_AddRefs(domDoc));
-      nsCOMPtr<nsIDocument> doc(do_QueryInterface(domDoc));
+      nsCOMPtr<nsIDocument> doc(GetDocument());
 
       if (SameCOMIdentity(subject, doc)) {
         nsCOMPtr<nsIDOMWindowUtils> utils(GetDOMWindowUtils());
@@ -1068,6 +1066,15 @@ TabChild::GetDOMWindowUtils()
   return utils.forget();
 }
 
+already_AddRefed<nsIDocument>
+TabChild::GetDocument()
+{
+  nsCOMPtr<nsIDOMDocument> domDoc;
+  mWebNav->GetDocument(getter_AddRefs(domDoc));
+  nsCOMPtr<nsIDocument> doc(do_QueryInterface(domDoc));
+  return doc.forget();
+}
+
 static nsInterfaceHashtable<nsPtrHashKey<PContentDialogChild>, nsIDialogParamBlock>* gActiveDialogs;
 
 NS_IMETHODIMP

dom/ipc/TabChild.h

@@ -451,6 +451,8 @@ private:
 
     // Get the DOMWindowUtils for the top-level window in this tab.
     already_AddRefed<nsIDOMWindowUtils> GetDOMWindowUtils();
+    // Get the Document for the top-level window in this tab.
+    already_AddRefed<nsIDocument> GetDocument();
 
     class CachedFileDescriptorInfo;
     class CachedFileDescriptorCallbackRunnable;