Don't close background pages if there is a pending response (callback).

chrome/browser/extensions/extension_event_router.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/extensions/extension_event_router.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/values.h"
 #include "chrome/browser/extensions/extension_devtools_manager.h"
@@ skipping 270 matching lines @@
     // incognito tab event sent to a normal process, or vice versa).
     bool cross_incognito = event->restrict_to_profile &&
         listener_profile != event->restrict_to_profile;
     // Send the event with different arguments to extensions that can't
     // cross incognito, if necessary.
     if (cross_incognito && !service->CanCrossIncognito(extension)) {
       if (!event->cross_incognito_args.empty()) {
         DispatchEvent(listener->process, listener->extension_id,
                       event->event_name, event->cross_incognito_args,
                       event->event_url);
+        IncrementInFlightEvents(listener->extension_id);
       }
       continue;
     }
 
     DispatchEvent(listener->process, listener->extension_id,
                   event->event_name, event->event_args, event->event_url);
+    IncrementInFlightEvents(listener->extension_id);
   }
 }
 
+void ExtensionEventRouter::IncrementInFlightEvents(
+    const std::string& extension_id) {
+  if (CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kEnableLazyBackgroundPages))
+    in_flight_events_[extension_id]++;
+}
+
+void ExtensionEventRouter::OnExtensionEventAck(
+    const std::string& extension_id) {
+  CHECK(CommandLine::ForCurrentProcess()->HasSwitch(
+      switches::kEnableLazyBackgroundPages));
+  CHECK(in_flight_events_[extension_id] > 0);
+  in_flight_events_[extension_id]--;
+}
+
+bool ExtensionEventRouter::HasInFlightEvents(const std::string& extension_id) {
+  return in_flight_events_[extension_id] > 0;
+}
+
 void ExtensionEventRouter::AppendEvent(
     const linked_ptr<ExtensionEvent>& event) {
   PendingEventsList* events_list = NULL;
   PendingEventsPerExtMap::iterator it =
       pending_events_.find(event->extension_id);
   if (it == pending_events_.end()) {
     events_list = new PendingEventsList();
     pending_events_[event->extension_id] =
         linked_ptr<PendingEventsList>(events_list);
   } else {
@@ skipping 51 matching lines @@
       ExtensionHost* eh = content::Details<ExtensionHost>(details).ptr();
       DispatchPendingEvents(eh->extension_id());
       break;
     }
     // TODO(tessamac): if background page crashed/failed clear queue.
     default:
       NOTREACHED();
       return;
   }
 }