Cleanups in the Mojo package.

mojo/dart/packages/mojo/lib/src/buffer.dart

 // 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.
 
 part of core;
 
 class MojoSharedBuffer {
-  static const int createFlagNone = 0;
-  static const int duplicateFlagNone = 0;
-  static const int mapFlagNone = 0;
+  static const int createFlagNone = MojoConstants.kNone;

[zra, 2016/02/16 16:58:26]

This indirection increases the amount of compilation we have to do at startup,
which will hurt startup time. What is the reason for the indirection?

[floitsch, 2016/02/16 17:03:54]

The constants are defined by the internal library and not the public package.
For example, the documentation of the internal library can't reference these
constants (even though it's the own defining what they actually mean).

Ideally the constants in MojoConstants should reference the ones in C, but that
seems to be too complicated.

+  static const int duplicateFlagNone = MojoConstants.kNone;
+  static const int mapFlagNone = MojoConstants.kNone;
 
   MojoHandle _handle;
   int _status = MojoResult.kOk;
 
   MojoHandle get handle => _handle;
   int get status => _status;
 
   MojoSharedBuffer(this._handle, [this._status = MojoResult.kOk]);
 
   factory MojoSharedBuffer.create(int numBytes, [int flags = createFlagNone]) {
@@ skipping 43 matching lines @@
     List result =
         MojoSharedBufferNatives.Map(handle.h, offset, numBytes, flags);
     if (result == null) {
       _status = MojoResult.kInvalidArgument;
       return null;
     }
     _status = result[0];
     return result[1];
   }
 }