Try to restore 'package:' URI reference to the file being moved.

pkg/analysis_server/lib/src/services/refactoring/move_file.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 services.src.refactoring.move_file;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/protocol.dart' hide Element;
 import 'package:analysis_server/src/services/correction/status.dart';
@@ skipping 44 matching lines @@
   }
 
   @override
   Future<SourceChange> createChange() {
     change = new SourceChange(refactoringName);
     List<Source> librarySources = context.getLibrariesContaining(source);
     return Future.forEach(librarySources, (Source librarySource) {
       CompilationUnitElement unitElement =
           context.getCompilationUnitElement(source, librarySource);
       if (unitElement != null) {
-        // update reference to the unit
-        searchEngine.searchReferences(unitElement).then((matches) {
-          List<SourceReference> references = getSourceReferences(matches);
-          for (SourceReference reference in references) {
-            String refDir = pathos.dirname(reference.file);
-            String newUri = pathos.relative(newFile, from: refDir);
-            change.addElementEdit(
-                reference.element,
-                createReferenceEdit(reference, "'$newUri'"));
-          }
-        });
         // if a defining unit, update outgoing references
         library = unitElement.library;
         if (library.definingCompilationUnit == unitElement) {
           oldLibraryDir = pathos.dirname(oldFile);
           newLibraryDir = pathos.dirname(newFile);
-          // update references to the imported/exported libraries
           _updateUriReferences(library.imports);
           _updateUriReferences(library.exports);
-          // update references to the sources units
-          for (CompilationUnitElement unit in library.parts) {
-            _updateUriReference(unit);
+          _updateUriReferences(library.parts);
+        }
+        // update reference to the unit
+        return searchEngine.searchReferences(unitElement).then((matches) {
+          List<SourceReference> references = getSourceReferences(matches);
+          for (SourceReference reference in references) {
+            String newUri = _computeNewUri(reference);
+            SourceEdit edit = createReferenceEdit(reference, "'$newUri'");
+            change.addElementEdit(reference.element, edit);
           }
-        }
+        });
       }
     }).then((_) {
       return change;
     });
   }
 
   @override
   bool requiresPreview() => false;
 
+  /**
+   * Computes the URI to use to reference [newFile] from [reference].
+   */
+  String _computeNewUri(SourceReference reference) {
+    String refDir = pathos.dirname(reference.file);
+    // try to keep package: URI
+    if (_isPackageReference(reference)) {
+      Source newSource = new NonExistingSource(newFile, UriKind.FILE_URI);
+      Uri restoredUri = context.sourceFactory.restoreUri(newSource);
+      if (restoredUri != null) {
+        return restoredUri.toString();
+      }
+    }
+    // if no package: URI, prepare relative
+    return pathos.relative(newFile, from: refDir);
+  }
+
+  bool _isPackageReference(SourceReference reference) {
+    Source source = reference.element.source;
+    int offset = reference.range.offset + "'".length;
+    String content = context.getContents(source).data;
+    return content.startsWith('package:', offset);
+  }
+
   void _updateUriReference(UriReferencedElement element) {
     if (!element.isSynthetic) {
       String elementUri = element.uri;
       if (_isRelativeUri(elementUri)) {
         String elementPath = pathos.join(oldLibraryDir, elementUri);
         String newUri = pathos.relative(elementPath, from: newLibraryDir);
         int uriOffset = element.uriOffset;
         int uriLength = element.uriEnd - uriOffset;
         change.addElementEdit(
             library,
@@ skipping 21 matching lines @@
       return false;
     }
     // absolute URI
     if (Uri.parse(path).isAbsolute) {
       return false;
     }
     // OK
     return true;
   }
 }