Cherry-pick r44373, r44378, and r44275.

pkg/analysis_server/lib/src/operation/operation.dart

 // Copyright (c) 2014, 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 operation;
 
 import 'package:analysis_server/src/analysis_server.dart';
+import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/source.dart';
 
 /**
  * The class [ServerOperation] defines the behavior of objects used to perform
  * operations on a [AnalysisServer].
  */
 abstract class ServerOperation {
   /**
+   * The context for this operation.  Operations will be automatically
+   * de-queued when their context is destroyed.
+   */
+  final AnalysisContext context;
+
+  ServerOperation(this.context);
+
+  /**
    * Returns the priority of this operation.
    */
   ServerOperationPriority get priority;
 
   /**
    * Performs the operation implemented by this operation.
    */
   void perform(AnalysisServer server);
 }
 
@@ skipping 30 matching lines @@
 
   @override
   String toString() => name;
 }
 
 /**
  * [SourceSensitiveOperation] can decide if the operation should be discarded
  * before a change is applied to a [Source].
  */
 abstract class SourceSensitiveOperation extends ServerOperation {
+  SourceSensitiveOperation(AnalysisContext context) : super(context);
+
   /**
    * The given [source] is about to be changed.
    * Check if this [SourceSensitiveOperation] should be discarded.
    */
   bool shouldBeDiscardedOnSourceChange(Source source);
 }