IPC: Fix attachment brokering race condition.

ipc/ipc_test_base.h

 // 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.
 
 #ifndef IPC_IPC_TEST_BASE_H_
 #define IPC_IPC_TEST_BASE_H_
 
 #include <memory>
 #include <string>
 
@@ skipping 87 matching lines @@
 
   // Use this to send IPC messages (when you don't care if you're using a
   // channel or a proxy).
   IPC::Sender* sender() {
     return channel_.get() ? static_cast<IPC::Sender*>(channel_.get()) :
                             static_cast<IPC::Sender*>(channel_proxy_.get());
   }
 
   IPC::Channel* channel() { return channel_.get(); }
   IPC::ChannelProxy* channel_proxy() { return channel_proxy_.get(); }
+  void set_channel_proxy(std::unique_ptr<IPC::ChannelProxy> proxy) {
+    DCHECK(!channel_proxy_);
+    channel_proxy_.swap(proxy);
+  }
 
   const base::Process& client_process() const { return client_process_; }
   scoped_refptr<base::SequencedTaskRunner> task_runner();
 
   virtual std::unique_ptr<IPC::ChannelFactory> CreateChannelFactory(
       const IPC::ChannelHandle& handle,
       base::SequencedTaskRunner* runner);
 
   virtual bool DidStartClient();
 
  private:
   std::string GetTestMainName() const;
 
   std::string test_client_name_;
   std::unique_ptr<base::MessageLoop> message_loop_;
 
   std::unique_ptr<IPC::Channel> channel_;
   std::unique_ptr<IPC::ChannelProxy> channel_proxy_;
 
   base::Process client_process_;
 
   DISALLOW_COPY_AND_ASSIGN(IPCTestBase);
 };
 
 // Use this to declare the client side for tests using IPCTestBase.
 #define MULTIPROCESS_IPC_TEST_CLIENT_MAIN(test_client_name) \
     MULTIPROCESS_IPC_TEST_MAIN(test_client_name ## TestClientMain)
 
 #endif  // IPC_IPC_TEST_BASE_H_