Initial support for an explicit plugin list

pkg/analysis_server/lib/src/plugin/plugin_watcher.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 'package:analysis_server/src/plugin/plugin_locator.dart';
 import 'package:analysis_server/src/plugin/plugin_manager.dart';
 import 'package:analyzer/context/context_root.dart';
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/source/package_map_resolver.dart';
 import 'package:analyzer/src/dart/analysis/driver.dart';
 import 'package:analyzer/src/dart/analysis/file_state.dart';
 import 'package:analyzer/src/util/absolute_path.dart';
+import 'package:front_end/src/base/source.dart';
+import 'package:path/src/context.dart';
 
 /**
  * An object that watches the results produced by analysis drivers to identify
  * references to previously unseen packages and, if those packages have plugins
  * associated with them, causes the plugin to be associated with the driver's
  * context root (which in turn might cause the plugin to be started).
  */
 class PluginWatcher implements DriverWatcher {
   /**
    * The resource provider used to access the file system.
@@ skipping 22 matching lines @@
   PluginWatcher(this.resourceProvider, this.manager)
       : _locator = new PluginLocator(resourceProvider);
 
   /**
    * The context manager has just added the given analysis [driver]. This method
    * must be called before the driver has been allowed to perform any analysis.
    */
   void addedDriver(AnalysisDriver driver, ContextRoot contextRoot) {
     _driverInfo[driver] = new _DriverInfo(
         contextRoot, <String>[contextRoot.root, _getSdkPath(driver)]);
-    driver.fsState.knownFilesSetChanges.listen((KnownFilesSetChange change) {
-      List<String> addedPluginPaths = _checkPluginsFor(driver, change);
-      for (String pluginPath in addedPluginPaths) {
-        manager.addPluginToContextRoot(contextRoot, pluginPath);
+    List<String> enabledPlugins = driver.analysisOptions.enabledPluginNames;
+    if (enabledPlugins.isNotEmpty) {
+      for (String package in enabledPlugins) {
+        //
+        // Determine whether the package exists and defines a plugin.
+        //
+        Source source =
+            driver.sourceFactory.forUri('package:$package/$package.dart');
+        Context context = resourceProvider.pathContext;
+        String packageRoot = context.dirname(context.dirname(source.fullName));
+        String pluginPath = _locator.findPlugin(packageRoot);
+        if (pluginPath != null) {
+          //
+          // Add the plugin to the context root.
+          //
+          // TODO(brianwilkerson) Do we need to wait for the plugin to be added?
+          // If we don't, then tests don't have any way to know when to expect
+          // that the list of plugins has been updated.
+          manager.addPluginToContextRoot(contextRoot, pluginPath);
+        }
       }
-    });
+    } else {
+      //
+      // Remove this code after users are switched over to use an explicit list
+      // of plugins.
+      //
+      driver.fsState.knownFilesSetChanges.listen((KnownFilesSetChange change) {
+        List<String> addedPluginPaths = _checkPluginsFor(driver, change);
+        for (String pluginPath in addedPluginPaths) {
+          manager.addPluginToContextRoot(contextRoot, pluginPath);
+        }
+      });
+    }
   }
 
   /**
    * The context manager has just removed the given analysis [driver].
    */
   void removedDriver(AnalysisDriver driver) {
     _DriverInfo info = _driverInfo[driver];
     if (info == null) {
       throw new StateError('Cannot remove a driver that was not added');
     }
@@ skipping 85 matching lines @@
    * A list of the absolute paths of directories inside of which we have already
    * searched for a plugin.
    */
   final List<String> packageRoots;
 
   /**
    * Initialize a newly created information holder.
    */
   _DriverInfo(this.contextRoot, this.packageRoots);
 }