From 8d9dc9efac8939d5de665066375b1139ba5e9cb1 Mon Sep 17 00:00:00 2001
From: Bill McCloskey <billm@mozilla.com>
Date: Tue, 29 Sep 2015 15:46:23 -0700
Subject: [PATCH] Bug 967873 - Allow RemotePrompt to be closed while it's being
 opened (r=Gijs)

---
 browser/modules/RemotePrompt.jsm | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/browser/modules/RemotePrompt.jsm b/browser/modules/RemotePrompt.jsm
index 1e142be2dab..041b8a3effc 100644
--- a/browser/modules/RemotePrompt.jsm
+++ b/browser/modules/RemotePrompt.jsm
@@ -39,11 +39,18 @@ var RemotePrompt = {
     let tabPrompt = window.gBrowser.getTabModalPromptBox(browser)
     let callbackInvoked = false;
     let newPrompt;
+    let needRemove = false;
     let promptId = args._remoteId;
 
     function onPromptClose(forceCleanup) {
+      // It's possible that we removed the prompt during the
+      // appendPrompt call below. In that case, newPrompt will be
+      // undefined. We set the needRemove flag to remember to remove
+      // it right after we've finished adding it.
       if (newPrompt)
         tabPrompt.removePrompt(newPrompt);
+      else
+        needRemove = true;
 
       PromptUtils.fireDialogEvent(window, "DOMModalDialogClosed", browser);
       browser.messageManager.sendAsyncMessage("Prompt:Close", args);
@@ -69,6 +76,10 @@ var RemotePrompt = {
 
       newPrompt = tabPrompt.appendPrompt(args, onPromptClose);
 
+      if (needRemove) {
+        tabPrompt.removePrompt(newPrompt);
+      }
+
       // TODO since we don't actually open a window, need to check if
       // there's other stuff in nsWindowWatcher::OpenWindowInternal
       // that we might need to do here as well.