Add deletion observer to P2PSocketDispatcher.

content/renderer/p2p/socket_dispatcher.h

Index: content/renderer/p2p/socket_dispatcher.h
diff --git a/content/renderer/p2p/socket_dispatcher.h b/content/renderer/p2p/socket_dispatcher.h
index 8cebd5190f221f9eb26568fb7e6ac149482da7f3..b4936ea7e8cc88bb78701b0d3ded55692e3e9870 100644
--- a/content/renderer/p2p/socket_dispatcher.h
+++ b/content/renderer/p2p/socket_dispatcher.h
@@ -52,6 +52,18 @@ namespace content {
 class P2PHostAddressRequest;
 class P2PSocketClient;
 
+// Callback interface that allows the implementor to be notified before a
+// P2PSocketDispatcher is destroyed.
+// P2PSocketDispatcher requires that all NetworkListObservers are
+// unregistered when SocketDispatcherGone is called.
+class P2PSocketDispatcherDestructionObserver {
+ public:
+  virtual void OnSocketDispatcherDestroyed() = 0;
+
+ protected:
+  virtual ~P2PSocketDispatcherDestructionObserver() {}
+};
+
 class CONTENT_EXPORT P2PSocketDispatcher : public content::RenderViewObserver {
  public:
   explicit P2PSocketDispatcher(RenderViewImpl* render_view);
@@ -69,6 +81,10 @@ class CONTENT_EXPORT P2PSocketDispatcher : public content::RenderViewObserver {
   void RemoveNetworkListObserver(
       webkit_glue::NetworkListObserver* network_list_observer);
 
+  void AddDestructionObserver(P2PSocketDispatcherDestructionObserver* observer);
+  void RemoveDestructionObserver(
+      P2PSocketDispatcherDestructionObserver* observer);
+
   // RenderViewObserver overrides.
   virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
 
@@ -111,6 +127,8 @@ class CONTENT_EXPORT P2PSocketDispatcher : public content::RenderViewObserver {
 
   scoped_refptr<AsyncMessageSender> async_message_sender_;
 
+  ObserverList<P2PSocketDispatcherDestructionObserver> destruction_observer_;
+
   DISALLOW_COPY_AND_ASSIGN(P2PSocketDispatcher);
 };