Use WorkManager(s) in AnalysisDriver.

pkg/analyzer/lib/src/task/dart_work_manager.dart

Index: pkg/analyzer/lib/src/task/dart_work_manager.dart
diff --git a/pkg/analyzer/lib/src/task/dart_work_manager.dart b/pkg/analyzer/lib/src/task/dart_work_manager.dart
index 76019f04bb51d5c8018327b3310f33a502d86081..d37bb32d547a2c8281401e212e7c2f8b2368d9b4 100644
--- a/pkg/analyzer/lib/src/task/dart_work_manager.dart
+++ b/pkg/analyzer/lib/src/task/dart_work_manager.dart
@@ -67,6 +67,10 @@ class DartWorkManager implements WorkManager {
     // library queue
     librarySourceQueue.removeAll(changedSources);
     librarySourceQueue.removeAll(removedSources);
+    // TODO(scheglov) This is an inefficient implementation.
+    // We could make the cache to return invalidated results and use them
+    // to allow work managers to schedule work request.
+    librarySourceQueue.addAll(librarySources);
   }
 
   @override
@@ -104,6 +108,14 @@ class DartWorkManager implements WorkManager {
   }
 
   @override
+  WorkOrderPriority getNextResultPriority() {
+    if (unknownSourceQueue.isNotEmpty || librarySourceQueue.isNotEmpty) {
+      return WorkOrderPriority.NORMAL;
+    }
+    return WorkOrderPriority.NONE;
+  }
+
+  @override
   void resultsComputed(
       AnalysisTarget target, Map<ResultDescriptor, dynamic> outputs) {
     // Organize sources.