Mojo: First stab at making MessagePipes work across OS pipes.

mojo/system/message_pipe_unittest.cc

 // 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.
 
 #include "mojo/system/message_pipe.h"
 
 #include "base/memory/ref_counted.h"
 #include "base/threading/platform_thread.h"  // For |Sleep()|.
 #include "base/time/time.h"
 #include "mojo/system/waiter.h"
@@ skipping 177 matching lines @@
   buffer_size = kBufferSize;
   EXPECT_EQ(MOJO_RESULT_OK,
             mp->ReadMessage(1,
                             buffer, &buffer_size,
                             NULL, NULL,
                             MOJO_READ_MESSAGE_FLAG_NONE));
   EXPECT_EQ(static_cast<uint32_t>(sizeof(buffer[0])), buffer_size);
   EXPECT_EQ(345678901, buffer[0]);
   EXPECT_EQ(456, buffer[1]);
 
-  // Read again from port 1 -- it should be empty.
+  // Read again from port 1 -- it should be empty (and port 0 is closed).
   buffer_size = kBufferSize;
-  EXPECT_EQ(MOJO_RESULT_NOT_FOUND,
+  EXPECT_EQ(MOJO_RESULT_FAILED_PRECONDITION,
             mp->ReadMessage(1,
                             buffer, &buffer_size,
                             NULL, NULL,
                             MOJO_READ_MESSAGE_FLAG_NONE));
 
   mp->Close(1);
 }
 
 TEST(MessagePipeTest, CloseWithQueuedIncomingMessages) {
   scoped_refptr<MessagePipe> mp(new MessagePipe());
@@ skipping 296 matching lines @@
 
     mp->CancelAllWaiters(1);
     mp->Close(1);
   }  // Joins |thread|.
   EXPECT_EQ(MOJO_RESULT_FAILED_PRECONDITION, result);
 }
 
 }  // namespace
 }  // namespace system
 }  // namespace mojo