[Extensions] Make port creation synchronous in unload handlers

extensions/renderer/messaging_bindings.h

 // Copyright 2014 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.
 
 #ifndef EXTENSIONS_RENDERER_MESSAGING_BINDINGS_H_
 #define EXTENSIONS_RENDERER_MESSAGING_BINDINGS_H_
 
 #include <string>
 
 #include "base/macros.h"
@@ skipping 97 matching lines @@
   int GetNextLocalId();
 
   // Active ports, mapped by local port id.
   PortMap ports_;
 
   // Ports which are disconnected, but haven't been fully initialized. Once
   // initialized and any pending messages are sent, these ports are removed.
   PortMap disconnected_ports_;
 
   // The next available local id for a port.
-  int next_local_id_ = 0;
+  size_t next_local_id_ = 0;
+
+  // The number of ports created in the 'beforeunload' event handler.
+  size_t ports_created_in_before_unload_ = 0;
+
+  // The number of ports created in the 'unload' event handler.
+  size_t ports_created_in_unload_ = 0;
+
+  // The number of ports created during during any time that isn't in the unload
+  // or beforeunload handlers.
+  int ports_created_normal_ = 0;
 
   base::WeakPtrFactory<MessagingBindings> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(MessagingBindings);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_RENDERER_MESSAGING_BINDINGS_H_