Address review feedback from pull request #30

packages/flutter_tools/lib/src/artifacts.dart

@@ -7,6 +7,10 @@ library sky_tools.artifacts;
 import 'dart:async';
 import 'dart:io';
 
+import 'package:logging/logging.dart';
+
+final Logger _logging = new Logger('sky_tools.device');
+
 enum Artifact {
   FlutterCompiler,
 }
@@ -15,13 +19,16 @@ class _ArtifactStore {
   _ArtifactStore._();
 
   Future _downloadFile(String url, File file) async {
-      HttpClient httpClient = new HttpClient();
-      HttpClientRequest request = await httpClient.getUrl(Uri.parse(url));
-      HttpClientResponse response = await request.close();
-      if (response.statusCode != 200) throw new Exception(response.reasonPhrase);
-      IOSink sink = file.openWrite();
-      await sink.addStream(response);
-      await sink.close();
+    _logging.fine('Downloading $url to ${file.path}');
+    HttpClient httpClient = new HttpClient();
+    HttpClientRequest request = await httpClient.getUrl(Uri.parse(url));
+    HttpClientResponse response = await request.close();
+    _logging.fine('Received response');
+    if (response.statusCode != 200) throw new Exception(response.reasonPhrase);
+    IOSink sink = file.openWrite();
+    await sink.addStream(response);
+    await sink.close();
+    _logging.fine('Wrote file');
   }
 
   Future<String> _getEngineRevision(String packageRoot) {
@@ -44,7 +51,7 @@ class _ArtifactStore {
     if (artifact == Artifact.FlutterCompiler) {
       File skySnapshotFile = new File(cacheDir.path + 'sky_snapshot');
       if (!await skySnapshotFile.exists()) {
-        print('Downloading sky_snapshot from the cloud, one moment please...');
+        _logging.info('Downloading sky_snapshot from the cloud, one moment please...');
         String googleStorageUrl = 'https://storage.googleapis.com/mojo/sky/shell/linux-x64/${engineRevision}/sky_snapshot';
         await _downloadFile(googleStorageUrl, skySnapshotFile);
         ProcessResult result = await Process.run('chmod', ['u+x', skySnapshotFile.path]);