Rationalize Dart mojo and sky package structure

mojo/public/dart/src/drain_data.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 DataPipeDrainer {
-  MojoDataPipeConsumer _consumer;
-  MojoEventStream _eventStream;
-  List<ByteData> _dataList;
-  int _dataSize;
-
-  DataPipeDrainer(this._consumer) {
-    _eventStream = new MojoEventStream(_consumer.handle);
-    _dataList = new List();
-    _dataSize = 0;
-  }
-
-  ByteData _copy(ByteData byteData) =>
-      new ByteData.view(
-          new Uint8List.fromList(byteData.buffer.asUint8List()).buffer);
-
-  MojoResult _doRead() {
-    ByteData thisRead = _consumer.beginRead();
-    if (thisRead == null) {
-      throw 'Data pipe beginRead failed: ${_consumer.status}';
-    }
-    _dataList.add(_copy(thisRead));
-    _dataSize += thisRead.lengthInBytes;
-    return _consumer.endRead(thisRead.lengthInBytes);
-  }
-
-  ByteData _concatData() {
-    var data = new ByteData(_dataSize);
-    int end = 0;
-    for (var chunk in _dataList) {
-      data.buffer.asUint8List().setRange(
-          end, end + chunk.lengthInBytes, chunk.buffer.asUint8List());
-      end += chunk.lengthInBytes;
-    }
-    return data;
-  }
-
-  Future<ByteData> drain() {
-    var completer = new Completer();
-    _eventStream.listen((List<int> event) {
-      var mojoSignals = new MojoHandleSignals(event[1]);
-      if (mojoSignals.isReadable) {
-        var result = _doRead();
-        if (!result.isOk) {
-          _eventStream.close();
-          _eventStream = null;
-          completer.complete(_concatData());
-        } else {
-          _eventStream.enableReadEvents();
-        }
-      } else if (mojoSignals.isPeerClosed) {
-        _eventStream.close();
-        _eventStream = null;
-        completer.complete(_concatData());
-      } else {
-        throw 'Unexpected handle event: $mojoSignals';
-      }
-    });
-    return completer.future;
-  }
-
-  static Future<ByteData> drainHandle(MojoDataPipeConsumer consumer) {
-    var drainer = new DataPipeDrainer(consumer);
-    return drainer.drain();
-  }
-}