Add an "onPlatform" parameter to test() and group().

lib/src/runner/browser/browser_manager.dart

 // Copyright (c) 2015, 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 test.runner.browser.browser_manager;
 
 import 'dart:async';
 import 'dart:convert';
 
 import 'package:http_parser/http_parser.dart';
 
 import '../../backend/metadata.dart';
 import '../../backend/suite.dart';
+import '../../backend/test_platform.dart';
 import '../../util/multi_channel.dart';
 import '../../util/remote_exception.dart';
 import '../../utils.dart';
 import '../load_exception.dart';
 import 'iframe_test.dart';
 
 /// A class that manages the connection to a single running browser.
 ///
 /// This is in charge of telling the browser which test suites to load and
 /// converting its responses into [Suite] objects.
 class BrowserManager {
+  /// The browser that this is managing.
+  TestPlatform browser;
+
   /// The channel used to communicate with the browser.
   ///
   /// This is connected to a page running `static/host.dart`.
   final MultiChannel _channel;
 
-  /// Creates a new BrowserManager that communicates with a browser over
+  /// Creates a new BrowserManager that communicates with [browser] over
   /// [webSocket].
-  BrowserManager(CompatibleWebSocket webSocket)
+  BrowserManager(this.browser, CompatibleWebSocket webSocket)
       : _channel = new MultiChannel(
           webSocket.map(JSON.decode),
           mapSink(webSocket, JSON.encode));
 
   /// Tells the browser the load a test suite from the URL [url].
   ///
   /// [url] should be an HTML page with a reference to the JS-compiled test
   /// suite. [path] is the path of the original test suite file, which is used
   /// for reporting. [metadata] is the parsed metadata for the test suite.
   Future<Suite> loadSuite(String path, Uri url, Metadata metadata) {
-    url = url.replace(
-        fragment: Uri.encodeFull(JSON.encode(metadata.serialize())));
+    url = url.replace(fragment: Uri.encodeFull(JSON.encode({
+      "metadata": metadata.serialize(),
+      "browser": browser.identifier
+    })));
 
     var suiteChannel = _channel.virtualChannel();
     _channel.sink.add({
       "command": "loadSuite",
       "url": url.toString(),
       "channel": suiteChannel.id
     });
 
     // Create a nested MultiChannel because the iframe will be using a channel
     // wrapped within the host's channel.
     suiteChannel = new MultiChannel(suiteChannel.stream, suiteChannel.sink);
 
     // The stream may close before emitting a value if the browser is killed
     // prematurely (e.g. via Control-C).
     return maybeFirst(suiteChannel.stream)
         .timeout(new Duration(seconds: 7), onTimeout: () {
       throw new LoadException(
-          path, "Timed out waiting for the test suite to connect.");
+          path,
+          "Timed out waiting for the test suite to connect on "
+              "${browser.name}.");
     }).then((response) {
       if (response == null) return null;
 
       if (response["type"] == "loadException") {
         return new Future.error(new LoadException(path, response["message"]));
       } else if (response["type"] == "error") {
         var asyncError = RemoteException.deserialize(response["error"]);
         return new Future.error(
             new LoadException(path, asyncError.error),
             asyncError.stackTrace);
       }
 
       return new Suite(response["tests"].map((test) {
         var testMetadata = new Metadata.deserialize(test['metadata']);
         var testChannel = suiteChannel.virtualChannel(test['channel']);
         return new IframeTest(test['name'], testMetadata, testChannel);
       }), metadata: metadata, path: path);
     });
   }
 }