Mojo: (Theoretically) implement the read side of platform handle passing.

mojo/system/message_in_transit.h

 // Copyright 2013 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_SYSTEM_MESSAGE_IN_TRANSIT_H_
 #define MOJO_SYSTEM_MESSAGE_IN_TRANSIT_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 70 matching lines @@
     View(size_t message_size, const void* buffer);
 
     // Checks that the given |View| appears to be for a valid message, within
     // predetermined limits (e.g., |num_bytes()| and |main_buffer_size()|, that
     // |transport_data_buffer()|/|transport_data_buffer_size()| is for valid
     // transport data -- see |TransportData::ValidateBuffer()|).
     //
     // It returns true (and leaves |error_message| alone) if this object appears
     // to be a valid message (according to the above) and false, pointing
     // |*error_message| to a suitable error message, if not.
-    bool IsValid(const char** error_message) const;
+    bool IsValid(size_t serialized_platform_handle_size,
+                 const char** error_message) const;
 
     // API parallel to that for |MessageInTransit| itself (mostly getters for
     // header data).
     const void* main_buffer() const { return buffer_; }
     size_t main_buffer_size() const {
       return RoundUpMessageAlignment(sizeof(Header) + header()->num_bytes);
     }
     const void* transport_data_buffer() const {
       return (total_size() > main_buffer_size()) ?
           static_cast<const char*>(buffer_) + main_buffer_size() : NULL;
@@ skipping 138 matching lines @@
   // some reason.)
   scoped_ptr<DispatcherVector> dispatchers_;
 
   DISALLOW_COPY_AND_ASSIGN(MessageInTransit);
 };
 
 }  // namespace system
 }  // namespace mojo
 
 #endif  // MOJO_SYSTEM_MESSAGE_IN_TRANSIT_H_