Proposal for the 'edit.organizeDirectives' request.

R=brianwilkerson@google.com
BUG= https://github.com/dart-lang/sdk/issues/23921

Review URL: https://codereview.chromium.org//1258563008 .

pkg/analysis_server/tool/spec/generated/java/AnalysisServer.java

@@ -350,6 +350,23 @@ public interface AnalysisServer {
    */
   public void edit_getRefactoring(String kind, String file, int offset, int length, boolean validateOnly, RefactoringOptions options, GetRefactoringConsumer consumer);
 
+  /**
+   * {@code edit.organizeDirectives}
+   *
+   * Organizes all of the directives - removes unused imports and sorts directives of the given Dart
+   * file according to the Dart Style Guide.
+   *
+   * If a request is made for a file that does not exist, does not belong to an analysis root or is
+   * not a Dart file, FILE_NOT_ANALYZED will be generated.
+   *
+   * If directives of the Dart file cannot be organized, for example because it has scan or parse
+   * errors, or by other reasons, ORGANIZE_DIRECTIVES_ERROR will be generated. The message will
+   * provide datails about the reason.
+   *
+   * @param file The Dart file to organize directives in.
+   */
+  public void edit_organizeDirectives(String file, OrganizeDirectivesConsumer consumer);
+
   /**
    * {@code edit.sortMembers}
    *