Make Dispatcher::Type an enum class.

mojo/edk/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_EDK_SYSTEM_MESSAGE_IN_TRANSIT_H_
 #define MOJO_EDK_SYSTEM_MESSAGE_IN_TRANSIT_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
-#include <iosfwd>
+#include <ostream>
 #include <vector>
 
 #include "base/macros.h"
 #include "base/memory/aligned_memory.h"
 #include "base/memory/scoped_ptr.h"
 #include "mojo/edk/system/channel_endpoint_id.h"
 #include "mojo/edk/system/dispatcher.h"
 #include "mojo/edk/system/memory.h"
 #include "mojo/edk/system/system_impl_export.h"
 
@@ skipping 255 matching lines @@
 
   // Any dispatchers that may be attached to this message. These dispatchers
   // should be "owned" by this message, i.e., have a ref count of exactly 1. (We
   // allow a dispatcher entry to be null, in case it couldn't be duplicated for
   // some reason.)
   scoped_ptr<DispatcherVector> dispatchers_;
 
   DISALLOW_COPY_AND_ASSIGN(MessageInTransit);
 };
 
-// Stream operator for |MessageInTransit::Type| and |Subtype| so we can use
-// |CHECK_EQ()|, |EXPECT_EQ()|, etc.
-std::ostream& operator<<(std::ostream& out, MessageInTransit::Type type);
-std::ostream& operator<<(std::ostream& out, MessageInTransit::Subtype subtype);
+// So logging macros and |DCHECK_EQ()|, etc. work.
+MOJO_SYSTEM_IMPL_EXPORT inline std::ostream& operator<<(
+    std::ostream& out,
+    MessageInTransit::Type type) {
+  return out << static_cast<uint16_t>(type);
+}
+
+// So logging macros and |DCHECK_EQ()|, etc. work.
+MOJO_SYSTEM_IMPL_EXPORT inline std::ostream& operator<<(
+    std::ostream& out,
+    MessageInTransit::Subtype subtype) {
+  return out << static_cast<uint16_t>(subtype);
+}
 
 }  // namespace system
 }  // namespace mojo
 
 #endif  // MOJO_EDK_SYSTEM_MESSAGE_IN_TRANSIT_H_