Add support to pass the location of the analysis options file to plugins

pkg/analysis_server/test/src/plugin/plugin_manager_test.dart

 // Copyright (c) 2017, 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.
 
 import 'dart:async';
 import 'dart:io' as io;
 
 import 'package:analysis_server/src/plugin/notification_manager.dart';
 import 'package:analysis_server/src/plugin/plugin_manager.dart';
 import 'package:analyzer/context/context_root.dart';
@@ skipping 101 matching lines @@
   DiscoveredPluginInfo plugin;
 
   void setUp() {
     resourceProvider = new MemoryResourceProvider();
     notificationManager = new TestNotificationManager();
     plugin = new DiscoveredPluginInfo(pluginPath, executionPath, packagesPath,
         notificationManager, InstrumentationService.NULL_SERVICE);
   }
 
   test_addContextRoot() {
+    String optionsFilePath = '/pkg1/analysis_options.yaml';
     ContextRoot contextRoot1 = new ContextRoot('/pkg1', []);
+    contextRoot1.optionsFilePath = optionsFilePath;
+    PluginSession session = new PluginSession(plugin);
+    TestServerCommunicationChannel channel =
+        new TestServerCommunicationChannel(session);
+    plugin.currentSession = session;
     plugin.addContextRoot(contextRoot1);
     expect(plugin.contextRoots, [contextRoot1]);
     plugin.addContextRoot(contextRoot1);
     expect(plugin.contextRoots, [contextRoot1]);
+    List<Request> sentRequests = channel.sentRequests;
+    expect(sentRequests, hasLength(1));
+    List<Map> roots = sentRequests[0].params['roots'];
+    expect(roots[0]['optionsFile'], optionsFilePath);
   }
 
   test_creation() {
     expect(plugin.path, pluginPath);
     expect(plugin.executionPath, executionPath);
     expect(plugin.notificationManager, notificationManager);
     expect(plugin.contextRoots, isEmpty);
     expect(plugin.currentSession, isNull);
   }
 
@@ skipping 560 matching lines @@
   }
 
   @override
   void sendRequest(Request request) {
     sentRequests.add(request);
     if (request.method == 'plugin.shutdown') {
       session.handleOnDone();
     }
   }
 }