Add logging system to pub and sprinkle some logging in.

utils/pub/hosted_source.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 hosted_source;
 
 import 'dart:io' as io;
 import 'dart:json';
 import 'dart:uri';
 
 // TODO(nweiz): Make this import better.
 import '../../pkg/http/lib/http.dart' as http;
 import 'io.dart';
+import 'log.dart' as log;
 import 'package.dart';
 import 'pubspec.dart';
 import 'source.dart';
 import 'source_registry.dart';
 import 'utils.dart';
 import 'version.dart';
 
 /**
  * A package source that installs packages from a package hosting site that
  * uses the same API as pub.dartlang.org.
@@ skipping 42 matching lines @@
   /**
    * Downloads a package from the site and unpacks it.
    */
   Future<bool> install(PackageId id, String destPath) {
     var parsedDescription = _parseDescription(id.description);
     var name = parsedDescription.first;
     var url = parsedDescription.last;
 
     var fullUrl = "$url/packages/$name/versions/${id.version}.tar.gz";
 
-    print('Downloading $id...');
+    log.message('Downloading $id...');
 
     // Download and extract the archive to a temp directory.
     var tempDir;
     return Futures.wait([
       httpClient.send(new http.Request("GET", new Uri.fromString(fullUrl)))
           .transform((response) => response.stream),
       systemCache.createTempDir()
     ]).chain((args) {
       tempDir = args[1];
       return timeout(extractTarGz(args[0], tempDir), HTTP_TIMEOUT,
@@ skipping 81 matching lines @@
 
     var name = description["name"];
     if (name is! String) {
       throw new FormatException("The 'name' key must have a string value.");
     }
 
     var url = description.containsKey("url") ? description["url"] : defaultUrl;
     return new Pair<String, String>(name, url);
   }
 }