Ignore filtered event if an event matcher cannot be added.

extensions/renderer/event_bindings.cc

Index: extensions/renderer/event_bindings.cc
diff --git a/extensions/renderer/event_bindings.cc b/extensions/renderer/event_bindings.cc
index de99257c3824e78046708ef98c51fe8fc8ca15ed..d72c487d7931814f91d07754c52e60f2d55c45bb 100644
--- a/extensions/renderer/event_bindings.cc
+++ b/extensions/renderer/event_bindings.cc
@@ -272,14 +272,17 @@ void EventBindings::AttachFilteredEvent(
     filter = base::DictionaryValue::From(std::move(filter_value));
   }
 
-  // Hold onto a weak reference to |filter| so that it can be used after passing
-  // ownership to |event_filter|.
-  base::DictionaryValue* filter_weak = filter.get();
   int id = g_event_filter.Get().AddEventMatcher(
       event_name, ParseEventMatcher(std::move(filter)));
+  if (id == -1) {
+    args.GetReturnValue().Set(static_cast<int32_t>(-1));
+    return;
+  }
   attached_matcher_ids_.insert(id);
 
   // Only send IPCs the first time a filter gets added.
+  base::DictionaryValue* filter_weak =
+      g_event_filter.Get().GetEventMatcher(id)->value();

[Devlin, 2016/08/11 21:57:39]

I wonder if we should also DCHECK that we get an EventMatcher* value.  I'll
leave it up to you.

[meacer, 2016/08/11 22:04:28]

Done.

   std::string extension_id = context()->GetExtensionID();
   if (AddFilter(event_name, extension_id, *filter_weak)) {
     bool lazy = ExtensionFrameHelper::IsContextForEventPage(context());