Add appengine/gcloud/mustache dependencies.

pkg/appengine/lib/src/protobuf_api/rpc/rpc_service_base.dart

+// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+library rpc_service_base;
+
+import 'dart:async';
+import 'dart:io';
+
+import '../../../api/errors.dart';
+
+abstract class RPCServiceBase {
+  static ContentType RPC_CONTENT_TYPE =
+      new ContentType('application', 'octet-stream');
+
+  HttpClient _client;
+
+  RPCServiceBase() : _client = new HttpClient();
+
+  Future<List<int>> makeRequest(String host,
+                                int port,
+                                String path,
+                                List<int> data,
+                                Map<String, String> additionalHeaders) {
+    return _client.post(host, port, path).then((HttpClientRequest request) {
+      var headers = request.headers;
+      headers.contentType = RPC_CONTENT_TYPE;
+      headers.contentLength = data.length;
+
+      for (var key in additionalHeaders.keys) {
+        headers.set(key, additionalHeaders[key]);
+      }
+
+      request.add(data);
+      return request.close().then((HttpClientResponse response) {
+        if (response.statusCode != HttpStatus.OK) {
+          return response.drain().then((_) {
+            throw new ProtocolError("Http statusCode was "
+                "${response.statusCode} instead of ${HttpStatus.OK}");
+          });
+        }
+        return response.fold(new BytesBuilder(), (buffer, data) {
+          buffer.add(data);
+          return buffer;
+        }).then((BytesBuilder buffer) => buffer.takeBytes());
+      });
+    }).catchError((error) {
+      throw new NetworkError('$error $port $host');
+    });
+  }
+}