ipc: Create an unforgeable mechanism to get the process id of the sender.

ipc/ipc_channel_win.h

 // 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.
 
 #ifndef IPC_IPC_CHANNEL_WIN_H_
 #define IPC_IPC_CHANNEL_WIN_H_
 
 #include "ipc/ipc_channel.h"
 
 #include <queue>
@@ skipping 34 matching lines @@
   static bool IsNamedServerInitialized(const std::string& channel_id);
 
 
  private:
   // ChannelReader implementation.
   ReadState ReadData(char* buffer, int buffer_len, int* bytes_read) override;
   bool ShouldDispatchInputMessage(Message* msg) override;
   bool GetNonBrokeredAttachments(Message* msg) override;
   bool DidEmptyInputBuffers() override;
   void HandleInternalMessage(const Message& msg) override;
+  base::ProcessId GetSenderPID() override;
 
   static const base::string16 PipeName(const std::string& channel_id,
                                        int32* secret);
   bool CreatePipe(const IPC::ChannelHandle &channel_handle, Mode mode);
 
   bool ProcessConnection();
   bool ProcessOutgoingMessages(base::MessageLoopForIO::IOContext* context,
                                DWORD bytes_written);
 
   // Returns |false| on channel error.
@@ skipping 67 matching lines @@
   // |broker_| must outlive this instance.
   AttachmentBroker* broker_;
 
   base::WeakPtrFactory<ChannelWin> weak_factory_;
   DISALLOW_COPY_AND_ASSIGN(ChannelWin);
 };
 
 }  // namespace IPC
 
 #endif  // IPC_IPC_CHANNEL_WIN_H_