CPP bindings: DCHECK when a Callback is destructed without being invoked

mojo/public/cpp/bindings/lib/router.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 MOJO_PUBLIC_CPP_BINDINGS_LIB_ROUTER_H_
 #define MOJO_PUBLIC_CPP_BINDINGS_LIB_ROUTER_H_
 
 #include <map>
 
 #include "mojo/public/cpp/bindings/lib/connector.h"
 #include "mojo/public/cpp/bindings/lib/filter_chain.h"
 #include "mojo/public/cpp/bindings/lib/shared_data.h"
 #include "mojo/public/cpp/environment/environment.h"
 
 namespace mojo {
 namespace internal {
 
 class Router : public MessageReceiverWithResponder {
  public:
   Router(ScopedMessagePipeHandle message_pipe,
          FilterChain filters,
          const MojoAsyncWaiter* waiter = Environment::GetDefaultAsyncWaiter());
   ~Router() override;
 
   // Sets the receiver to handle messages read from the message pipe that do
   // not have the kMessageIsResponse flag set.
-  void set_incoming_receiver(MessageReceiverWithResponder* receiver) {
+  void set_incoming_receiver(MessageReceiverWithResponderStatus* receiver) {
     incoming_receiver_ = receiver;
   }
 
   // Sets the error handler to receive notifications when an error is
   // encountered while reading from the pipe or waiting to read from the pipe.
   void set_error_handler(ErrorHandler* error_handler) {
     connector_.set_error_handler(error_handler);
   }
 
   // Returns true if an error was encountered while reading from the pipe or
   // waiting to read from the pipe.
   bool encountered_error() const { return connector_.encountered_error(); }
 
+  // Is the router bound to a MessagePipe handle?
+  bool is_valid() const { return connector_.is_valid(); }
+
   void CloseMessagePipe() { connector_.CloseMessagePipe(); }
 
   ScopedMessagePipeHandle PassMessagePipe() {
     return connector_.PassMessagePipe();
   }
 
   // MessageReceiver implementation:
   bool Accept(Message* message) override;
   bool AcceptWithResponder(Message* message,
                            MessageReceiver* responder) override;
@@ skipping 23 matching lines @@
    private:
     Router* router_;
   };
 
   bool HandleIncomingMessage(Message* message);
 
   HandleIncomingMessageThunk thunk_;
   FilterChain filters_;
   Connector connector_;
   SharedData<Router*> weak_self_;
-  MessageReceiverWithResponder* incoming_receiver_;
+  MessageReceiverWithResponderStatus* incoming_receiver_;
   ResponderMap responders_;
   uint64_t next_request_id_;
   bool testing_mode_;
 };
 
 }  // namespace internal
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_CPP_BINDINGS_LIB_ROUTER_H_