webRequest: Check weak ptr before dispatching event

extensions/browser/api/web_request/web_request_api.cc

 // Copyright (c) 2012 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 "extensions/browser/api/web_request/web_request_api.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <utility>
@@ skipping 1054 matching lines @@
         event_listeners.find(target);
     // Ignore listener if it was removed between the thread hops.
     if (listener == event_listeners.end()) {
       if (!cross_event_listeners)
         continue;
       listener = cross_event_listeners->find(target);
       if (listener == cross_event_listeners->end())
         continue;
     }
 
+    if (!listener->ipc_sender.get())
+      continue;
+
     // Filter out the optional keys that this listener didn't request.
     scoped_ptr<base::ListValue> args_filtered(new base::ListValue);
     args_filtered->Append(
         event_details->GetFilteredDict(listener->extra_info_spec));
 
     EventRouter::DispatchEventToSender(
         listener->ipc_sender.get(), browser_context, listener->extension_id,
         listener->histogram_value, listener->sub_event_name,
         std::move(args_filtered), EventRouter::USER_GESTURE_UNKNOWN,
         EventFilteringInfo());
@@ skipping 1170 matching lines @@
   // Continue gracefully.
   RunSync();
 }
 
 bool WebRequestHandlerBehaviorChangedFunction::RunSync() {
   helpers::ClearCacheOnNavigation();
   return true;
 }
 
 }  // namespace extensions