Dart: Moves |native| methods to patch files.

mojo/dart/embedder/core/message_pipe_patch.dart

Index: mojo/dart/embedder/core/message_pipe_patch.dart
diff --git a/mojo/dart/embedder/core/message_pipe_patch.dart b/mojo/dart/embedder/core/message_pipe_patch.dart
index fd34d1f948f5ec7f1a52aa9c11ace583055636de..f7cf864c33ece335db6d8b09610c34b04ade4697 100644
--- a/mojo/dart/embedder/core/message_pipe_patch.dart
+++ b/mojo/dart/embedder/core/message_pipe_patch.dart
@@ -2,3 +2,15 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+patch class _MojoMessagePipeNatives {
+  static List MojoCreateMessagePipe(int flags)
+      native "MojoMessagePipe_Create";
+
+  static int MojoWriteMessage(
+      int handle, ByteData data, int numBytes, List<int> handles, int flags)
+      native "MojoMessagePipe_Write";
+
+  static List MojoReadMessage(
+      int handle, ByteData data, int numBytes, List<int> handles, int flags)
+      native "MojoMessagePipe_Read";
+}