Make TransportData (and thus MessageInTransit) be able to simply carry platform handles.

mojo/edk/system/transport_data.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_EDK_SYSTEM_TRANSPORT_DATA_H_
 #define MOJO_EDK_SYSTEM_TRANSPORT_DATA_H_
 
 #include <stdint.h>
 
 #include <vector>
@@ skipping 73 matching lines @@
   static const size_t kMaxSerializedDispatcherPlatformHandles = 2;
 
   // The maximum possible size of a valid transport data buffer.
   static size_t GetMaxBufferSize();
 
   // The maximum total number of platform handles that may be attached.
   static size_t GetMaxPlatformHandles();
 
   TransportData(scoped_ptr<DispatcherVector> dispatchers, Channel* channel);
 
-#if defined(OS_POSIX)
-  // This is a hacky POSIX-only constructor to directly attach only platform
-  // handles to a message, used by |RawChannelPosix| to split messages with too
-  // many platform handles into multiple messages. |Header| will be present, but
-  // be zero. (No other information will be attached, and
-  // |RawChannel::GetSerializedPlatformHandleSize()| should return zero.)
+  // This is used for users of |MessageInTransit|/|TransportData|/|RawChannel|
+  // that want to simply transport data and platform handles, and not
+  // |Dispatcher|s. (|Header| will be present, and zero except for
+  // |num_platform_handles|, and |platform_handle_table_offset| if necessary.)
   explicit TransportData(
       embedder::ScopedPlatformHandleVectorPtr platform_handles);
-#endif
 
   ~TransportData();
 
   const void* buffer() const { return buffer_.get(); }
   void* buffer() { return buffer_.get(); }
   size_t buffer_size() const { return buffer_size_; }
 
   uint32_t platform_handle_table_offset() const {
     return header()->platform_handle_table_offset;
   }
@@ skipping 60 matching lines @@
   const Header* header() const {
     return reinterpret_cast<const Header*>(buffer_.get());
   }
 
   size_t buffer_size_;
   scoped_ptr<char, base::AlignedFreeDeleter> buffer_;  // Never null.
 
   // Any platform-specific handles attached to this message (for inter-process
   // transport). The vector (if any) owns the handles that it contains (and is
   // responsible for closing them).
-  // TODO(vtl): With C++11, change it to a vector of |ScopedPlatformHandles|.
+  // TODO(vtl): With C++11, change it to a vector of |ScopedPlatformHandle|s.
   embedder::ScopedPlatformHandleVectorPtr platform_handles_;
 
   DISALLOW_COPY_AND_ASSIGN(TransportData);
 };
 
 }  // namespace system
 }  // namespace mojo
 
 #endif  // MOJO_EDK_SYSTEM_TRANSPORT_DATA_H_