Add BuildBotClient to abstract http/logdog access

tools/gardening/bin/current_summary.dart

Index: tools/gardening/bin/current_summary.dart
diff --git a/tools/gardening/bin/current_summary.dart b/tools/gardening/bin/current_summary.dart
index 78e813b59677beddb4b3c8645470c806c154ac3f..4155071bedbef4a3a9e59630df5219fb5dcb73bb 100644
--- a/tools/gardening/bin/current_summary.dart
+++ b/tools/gardening/bin/current_summary.dart
@@ -15,12 +15,18 @@ import 'package:args/args.dart';
 import 'package:gardening/src/buildbot_data.dart';
 import 'package:gardening/src/buildbot_loading.dart';
 import 'package:gardening/src/buildbot_structures.dart';
+import 'package:gardening/src/client.dart';
 import 'package:gardening/src/util.dart';
 
 main(List<String> args) async {
   ArgParser argParser = createArgParser();
   ArgResults argResults = argParser.parse(args);
   processArgResults(argResults);
+
+  BuildbotClient client = argResults['logdog']
+      ? new LogdogBuildbotClient()
+      : new HttpBuildbotClient();
+
   if (argResults.rest.length == 0) {
     print('Usage: current_summary [options] <test-name1> [<test-name2> ...]');
     print('where options are:');
@@ -30,15 +36,14 @@ main(List<String> args) async {
   int maxStatusWidth = 0;
   int maxConfigWidth = 0;
 
-  HttpClient client = new HttpClient();
   Map<String, Map<BuildUri, TestStatus>> resultMap =
       <String, Map<BuildUri, TestStatus>>{};
   for (BuildGroup group in buildGroups) {
     // TODO(johnniwinther): Support reading a partially completed shard, i.e.
     // use build number `-1`.
-    for (BuildUri buildUri in group.createUris(-2)) {
+    for (BuildUri buildUri in group.createUris(client.mostRecentBuildNumber)) {
       print('Reading $buildUri');
-      BuildResult buildResult = await readBuildResult(client, buildUri);
+      BuildResult buildResult = await client.readResult(buildUri);
       for (TestStatus testStatus in buildResult.results) {
         String testName = testStatus.config.testName;
         for (String arg in argResults.rest) {