Rip out dart:io from pkg/http wherever possible.

pkg/http/lib/src/base_client.dart

 // Copyright (c) 2012, 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 base_client;
 
 import 'dart:async';
 import 'dart:convert';
-import 'dart:io';
 import 'dart:typed_data';
 
 import 'base_request.dart';
 import 'client.dart';
+import 'exception.dart';
 import 'request.dart';
 import 'response.dart';
 import 'streamed_response.dart';
 import 'utils.dart';
 
 /// The abstract base class for an HTTP client. This is a mixin-style class;
 /// subclasses only need to implement [send] and maybe [close], and then they
 /// get various convenience methods for free.
 abstract class BaseClient implements Client {
   /// Sends an HTTP HEAD request with the given headers to the given URL, which
@@ skipping 58 matching lines @@
   /// which can be a [Uri] or a [String].
   ///
   /// For more fine-grained control over the request, use [send] instead.
   Future<Response> delete(url, {Map<String, String> headers}) =>
     _sendUnstreamed("DELETE", url, headers);
 
   /// Sends an HTTP GET request with the given headers to the given URL, which
   /// can be a [Uri] or a [String], and returns a Future that completes to the
   /// body of the response as a String.
   ///
-  /// The Future will emit an [HttpException] if the response doesn't have a
+  /// The Future will emit a [ClientException] if the response doesn't have a
   /// success status code.
   ///
   /// For more fine-grained control over the request and response, use [send] or
   /// [get] instead.
   Future<String> read(url, {Map<String, String> headers}) {
     return get(url, headers: headers).then((response) {
       _checkResponseSuccess(url, response);
       return response.body;
     });
   }
 
   /// Sends an HTTP GET request with the given headers to the given URL, which
   /// can be a [Uri] or a [String], and returns a Future that completes to the
   /// body of the response as a list of bytes.
   ///
-  /// The Future will emit an [HttpException] if the response doesn't have a
+  /// The Future will emit an [ClientException] if the response doesn't have a
   /// success status code.
   ///
   /// For more fine-grained control over the request and response, use [send] or
   /// [get] instead.
   Future<Uint8List> readBytes(url, {Map<String, String> headers}) {
     return get(url, headers: headers).then((response) {
       _checkResponseSuccess(url, response);
       return response.bodyBytes;
     });
   }
 
   /// Sends an HTTP request and asynchronously returns the response.
   ///
   /// Implementers should call [BaseRequest.finalize] to get the body of the
   /// request as a [ByteStream]. They shouldn't make any assumptions about the
   /// state of the stream; it could have data written to it asynchronously at a
-  /// later point, or it could already be closed when it's returned.
+  /// later point, or it could already be closed when it's returned. Any
+  /// internal HTTP errors should be wrapped as [ClientException]s.
   Future<StreamedResponse> send(BaseRequest request);
 
   /// Sends a non-streaming [Request] and returns a non-streaming [Response].
   Future<Response> _sendUnstreamed(String method, url,
       Map<String, String> headers, [body, Encoding encoding]) {
     return syncFuture(() {
       if (url is String) url = Uri.parse(url);
       var request = new Request(method, url);
 
       if (headers != null) request.headers.addAll(headers);
@@ skipping 14 matching lines @@
     }).then(Response.fromStream);
   }
 
   /// Throws an error if [response] is not successful.
   void _checkResponseSuccess(url, Response response) {
     if (response.statusCode < 400) return;
     var message = "Request to $url failed with status ${response.statusCode}";
     if (response.reasonPhrase != null) {
       message = "$message: ${response.reasonPhrase}";
     }
-    throw new HttpException("$message.");
+    if (url is String) url = Uri.parse(url);
+    throw new ClientException("$message.", url);
   }
 
   /// Closes the client and cleans up any resources associated with it. It's
   /// important to close each client when it's done being used; failing to do so
   /// can cause the Dart process to hang.
   void close() {}
 }