Bug 990812 - Let the frame loader use a group message manager as the parent when it detects that a frame belongs to a certain group r=smaug

content/base/src/nsFrameLoader.cpp

@@ -2425,9 +2425,20 @@ nsFrameLoader::EnsureMessageManager()
   nsCOMPtr<nsIDOMChromeWindow> chromeWindow =
     do_QueryInterface(GetOwnerDoc()->GetWindow());
   nsCOMPtr<nsIMessageBroadcaster> parentManager;
+
   if (chromeWindow) {
+    nsAutoString messagemanagergroup;
+    if (mOwnerContent->IsXUL() &&
+        mOwnerContent->GetAttr(kNameSpaceID_None,
+                               nsGkAtoms::messagemanagergroup,
+                               messagemanagergroup)) {
+      chromeWindow->GetGroupMessageManager(messagemanagergroup, getter_AddRefs(parentManager));
+    }
+
+    if (!parentManager) {
       chromeWindow->GetMessageManager(getter_AddRefs(parentManager));
     }
+  }
 
   if (ShouldUseRemoteProcess()) {
     mMessageManager = new nsFrameMessageManager(mRemoteBrowserShown ? this : nullptr,

content/base/src/nsGkAtomList.h

@@ -583,6 +583,7 @@ GK_ATOM(minpos, "minpos")
 GK_ATOM(minusSign, "minus-sign")
 GK_ATOM(minwidth, "minwidth")
 GK_ATOM(_mixed, "mixed")
+GK_ATOM(messagemanagergroup, "messagemanagergroup")
 GK_ATOM(mod, "mod")
 GK_ATOM(mode, "mode")
 GK_ATOM(modifiers, "modifiers")