Migrate DDC to the new analysis driver.

pkg/analyzer/lib/src/summary/package_bundle_reader.dart

 import 'dart:io' as io;
 
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/src/context/cache.dart';
 import 'package:analyzer/src/context/context.dart';
 import 'package:analyzer/src/dart/element/element.dart';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/resolver.dart' show TypeProvider;
 import 'package:analyzer/src/generated/source.dart';
@@ skipping 394 matching lines @@
    */
   void addUnlinkedUnit(String uri, UnlinkedUnit unlinkedUnit) {
     unlinkedMap[uri] = unlinkedUnit;
   }
 
   /**
    * Return a list of absolute URIs of the libraries that contain the unit with
    * the given [unitUriString], or `null` if no such library is in the store.
    */
   List<String> getContainingLibraryUris(String unitUriString) {
-
     // The unit is the defining unit of a library.
     if (linkedMap.containsKey(unitUriString)) {
       return <String>[unitUriString];
     }
     // Check every unlinked unit whether it uses [unitUri] as a part.
     List<String> libraryUriStrings = <String>[];
     unlinkedMap.forEach((unlinkedUnitUriString, unlinkedUnit) {
       Uri libraryUri = Uri.parse(unlinkedUnitUriString);
       for (String partUriString in unlinkedUnit.publicNamespace.parts) {
         Uri partUri = Uri.parse(partUriString);
         String partAbsoluteUriString =
             resolveRelativeUri(libraryUri, partUri).toString();
         if (partAbsoluteUriString == unitUriString) {
           libraryUriStrings.add(unlinkedUnitUriString);
         }
       }
     });
     return libraryUriStrings.isNotEmpty ? libraryUriStrings : null;
   }
 
+  /**
+   * Return `true` if the store contains the unlinked summary for the unit
+   * with the given absolute [uri].
+   */
+  bool hasUnlinkedUnit(String uri) {
+    return unlinkedMap.containsKey(uri);
+  }
+
   void _fillMaps(String path, ResourceProvider resourceProvider) {
     List<int> buffer;
     if (resourceProvider != null) {
       var file = resourceProvider.getFile(path);
       buffer = file.readAsBytesSync();
     } else {
       io.File file = new io.File(path);
       buffer = file.readAsBytesSync();
     }
     PackageBundle bundle = new PackageBundle.fromBuffer(buffer);
     addBundle(path, bundle);
   }
+
+  /**
+   * TODO(scheglov) document
+   */
+  void addStore(SummaryDataStore other) {
+    unlinkedMap.addAll(other.unlinkedMap);
+    linkedMap.addAll(other.linkedMap);
+  }
 }