Reland #2 "ipc: Add a new field num_brokered_attachments to the message header."

ipc/ipc_message.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_MESSAGE_H_
 #define IPC_IPC_MESSAGE_H_
 
 #include <stdint.h>
 
 #include <string>
 
 #include "base/memory/ref_counted.h"
 #include "base/pickle.h"
 #include "base/trace_event/trace_event.h"
+#include "ipc/attachment_broker.h"
 #include "ipc/brokerable_attachment.h"
 #include "ipc/ipc_export.h"
 
 #if !defined(NDEBUG)
 #define IPC_MESSAGE_LOG_ENABLED
 #endif
 
 namespace IPC {
 
 namespace internal {
@@ skipping 219 matching lines @@
   friend class ChannelWin;
   friend class internal::ChannelReader;
   friend class MessageReplyDeserializer;
   friend class SyncMessage;
 
 #pragma pack(push, 4)
   struct Header : base::Pickle::Header {
     int32_t routing;  // ID of the view that this message is destined for
     uint32_t type;    // specifies the user-defined message type
     uint32_t flags;   // specifies control flags for the message
+#if USE_ATTACHMENT_BROKER
+    // The number of brokered attachments included with this message. The
+    // ids of the brokered attachment ids are sent immediately after the pickled
+    // message, before the next pickled message is sent.
+    uint32_t num_brokered_attachments;
+#endif
 #if defined(OS_POSIX)
     uint16_t num_fds; // the number of descriptors included with this message
     uint16_t pad;     // explicitly initialize this to appease valgrind
 #endif
   };
 #pragma pack(pop)
 
   Header* header() {
     return headerT<Header>();
   }
@@ skipping 42 matching lines @@
   MSG_ROUTING_NONE = -2,
 
   // indicates a general message not sent to a particular tab.
   MSG_ROUTING_CONTROL = INT32_MAX,
 };
 
 #define IPC_REPLY_ID 0xFFFFFFF0  // Special message id for replies
 #define IPC_LOGGING_ID 0xFFFFFFF1  // Special message id for logging
 
 #endif  // IPC_IPC_MESSAGE_H_