Bug 1334080 - If a plugin is associated with a window that has no nsIWebNavigation, don't crash, r=qdot

MozReview-Commit-ID: CZLne2N498d

--HG--
extra : rebase_source : aac04a1c16824fde27e3869109e7e8b591ce9296

dom/plugins/base/nsPluginStreamListenerPeer.cpp

@@ -1291,19 +1291,28 @@ nsPluginStreamListenerPeer::GetInterfaceGlobal(const nsIID& aIID, void** result)
   }
 
   RefPtr<nsPluginInstanceOwner> owner = mPluginInstance->GetOwner();
-  if (owner) {
-    nsCOMPtr<nsIDocument> doc;
-    nsresult rv = owner->GetDocument(getter_AddRefs(doc));
-    if (NS_SUCCEEDED(rv) && doc) {
-      if  (nsPIDOMWindowOuter *window = doc->GetWindow()) {
-        nsCOMPtr<nsIWebNavigation> webNav = do_GetInterface(window);
-        nsCOMPtr<nsIInterfaceRequestor> ir = do_QueryInterface(webNav);
-        return ir->GetInterface(aIID, result);
-      }
-    }
+  if (!owner) {
+    return NS_ERROR_FAILURE;
   }
 
-  return NS_ERROR_FAILURE;
+  nsCOMPtr<nsIDocument> doc;
+  nsresult rv = owner->GetDocument(getter_AddRefs(doc));
+  if (NS_FAILED(rv) || !doc) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsPIDOMWindowOuter *window = doc->GetWindow();
+  if (!window) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsCOMPtr<nsIWebNavigation> webNav = do_GetInterface(window);
+  nsCOMPtr<nsIInterfaceRequestor> ir = do_QueryInterface(webNav);
+  if (!ir) {
+    return NS_ERROR_FAILURE;
+  }
+
+  return ir->GetInterface(aIID, result);
 }
 
 NS_IMETHODIMP