Add get_drt.py to test.dart, so that testing browser components updates DumpRenderTree.

tools/testing/dart/drt_updater.dart

Index: tools/testing/dart/drt_updater.dart
diff --git a/tools/testing/dart/drt_updater.dart b/tools/testing/dart/drt_updater.dart
new file mode 100644
index 0000000000000000000000000000000000000000..38736612d4132c4afdb43379a6c84a655fb3431e
--- /dev/null
+++ b/tools/testing/dart/drt_updater.dart
@@ -0,0 +1,46 @@
+// 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("drt_updater");
+
+#import("dart:io");
+#import("dart:builtin");
+
+class DumpRenderTreeUpdater {
+  static bool isActive = false;
+  static bool updated = false;
+  static List onUpdated;
+
+  static Process _updatingProcess;
+
+  static void update() {
+    if (!isActive) {
+      isActive = true;
+      print('Updating DumpRenderTree.');
+      onUpdated = [() {updated = true;} ];
+      _updatingProcess = new Process.start('python', [_getDrtPath]);
+      _updatingProcess.onExit = _onUpdatedHandler;
+      _updatingProcess.onError = (error) {
+        print("Error starting get_drt.py process: $error");
+        _onUpdatedHandler(-1);  // Continue anyway.
+      };
+    }
+  }
+
+  static bool componentRequiresDRT(String component) =>
+      const <String>['dartium',
+                     'frogium',
+                     'legium'].some((x) => x == component);
+
+  static String get _getDrtPath() {
+    String scriptPath = new Options().script.replaceAll('\\', '/');
+    String toolsDir = scriptPath.substring(0, scriptPath.lastIndexOf('/'));
+    return '$toolsDir/get_drt.py';
+  }
+
+  static void _onUpdatedHandler(int exit_code) {
+    print('DumpRenderTree updated ($exit_code)');
+    for (var callback in onUpdated ) callback();
+  }
+}