Migrate DDC to the new analysis driver.

pkg/analyzer/lib/src/dart/analysis/file_state.dart

Index: pkg/analyzer/lib/src/dart/analysis/file_state.dart
diff --git a/pkg/analyzer/lib/src/dart/analysis/file_state.dart b/pkg/analyzer/lib/src/dart/analysis/file_state.dart
index 11e3674946d17b84a8a4341eea58c226bfca8492..ae3fad2603a2ea1f410f3624a7c72e7e6b92b337 100644
--- a/pkg/analyzer/lib/src/dart/analysis/file_state.dart
+++ b/pkg/analyzer/lib/src/dart/analysis/file_state.dart
@@ -25,6 +25,7 @@ import 'package:analyzer/src/summary/api_signature.dart';
 import 'package:analyzer/src/summary/format.dart';
 import 'package:analyzer/src/summary/idl.dart';
 import 'package:analyzer/src/summary/name_filter.dart';
+import 'package:analyzer/src/summary/package_bundle_reader.dart';
 import 'package:analyzer/src/summary/summarize_ast.dart';
 import 'package:convert/convert.dart';
 import 'package:crypto/crypto.dart';
@@ -595,6 +596,18 @@ class FileSystemState {
   final Uint32List _salt;
 
   /**
+   * The optional store with externally provided unlinked and corresponding
+   * linked summaries. These summaries are always added to the store for any
+   * file analysis.
+   *
+   * While walking the file graph, when we reach a file that exists in the
+   * external store, we don't add it.
+   *
+   * TODO(scheglov) document some more
+   */
+  final SummaryDataStore externalSummaries;
+
+  /**
    * Mapping from a URI to the corresponding [FileState].
    */
   final Map<Uri, FileState> _uriToFile = {};
@@ -633,7 +646,8 @@ class FileSystemState {
       this._resourceProvider,
       this._sourceFactory,
       this._analysisOptions,
-      this._salt) {
+      this._salt,
+      {this.externalSummaries}) {
     _testView = new FileSystemStateTestView(this);
   }
 
@@ -685,12 +699,23 @@ class FileSystemState {
   FileState getFileForUri(Uri uri) {
     FileState file = _uriToFile[uri];
     if (file == null) {
-      Source uriSource = _sourceFactory.resolveUri(null, uri.toString());
+      String uriStr = uri.toString();
+
+      // If the external store has this URI, don't create the file for it.
+      // We are given all required unlinked and linked summaries for it.
+      if (externalSummaries != null &&
+          externalSummaries.hasUnlinkedUnit(uriStr)) {
+        return null;
+      }
+
+      Source uriSource = _sourceFactory.resolveUri(null, uriStr);
+
       // If the URI is invalid, for example package:/test/d.dart (note the
       // leading '/'), then `null` is returned. We should ignore this URI.
       if (uriSource == null) {
         return null;
       }
+
       String path = uriSource.fullName;
       File resource = _resourceProvider.getFile(path);
       FileSource source = new FileSource(resource, uri);
@@ -756,6 +781,9 @@ class FileSystemState {
       _pathToFiles[path] = files;
     }
     files.add(file);
+    if (file.uri.scheme != 'package') {
+      _pathToCanonicalFile[path] = file;
+    }
   }
 }