Add a Mojo EDK for Chrome that uses one OS pipe per message pipe.

mojo/edk/system/process_identifier.h

 // Copyright 2015 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_PROCESS_IDENTIFIER_H_
 #define MOJO_EDK_SYSTEM_PROCESS_IDENTIFIER_H_
 
 #include <stdint.h>
 
 namespace mojo {
-namespace system {
+namespace edk {
 
 // Identifiers for processes (note that these are not OS process IDs):
 using ProcessIdentifier = uint64_t;
 
 // Zero will never be a process identifier for any process.
 const ProcessIdentifier kInvalidProcessIdentifier = 0;
 
 // The master process will always have this process identifier.
 const ProcessIdentifier kMasterProcessIdentifier = 1;
 
-}  // namespace system
+}  // namespace edk
 }  // namespace mojo
 
 #endif  // MOJO_EDK_SYSTEM_PROCESS_IDENTIFIER_H_