Initial implementation of "Rename Local Variable" refactoring.

editor/tools/plugins/com.google.dart.tools.core/src/com/google/dart/tools/core/refactoring/descriptors/DartRefactoringContribution.java

Index: editor/tools/plugins/com.google.dart.tools.core/src/com/google/dart/tools/core/refactoring/descriptors/DartRefactoringContribution.java
diff --git a/editor/tools/plugins/com.google.dart.tools.core/src/com/google/dart/tools/core/refactoring/descriptors/DartRefactoringContribution.java b/editor/tools/plugins/com.google.dart.tools.core/src/com/google/dart/tools/core/refactoring/descriptors/DartRefactoringContribution.java
new file mode 100644
index 0000000000000000000000000000000000000000..41ac89f217ff4f4d197ffb0f050eb46405e147e6
--- /dev/null
+++ b/editor/tools/plugins/com.google.dart.tools.core/src/com/google/dart/tools/core/refactoring/descriptors/DartRefactoringContribution.java
@@ -0,0 +1,40 @@
+package com.google.dart.tools.core.refactoring.descriptors;
+
+import org.eclipse.core.runtime.Assert;
+import org.eclipse.core.runtime.CoreException;
+import org.eclipse.ltk.core.refactoring.Refactoring;
+import org.eclipse.ltk.core.refactoring.RefactoringContribution;
+import org.eclipse.ltk.core.refactoring.RefactoringDescriptor;
+import org.eclipse.ltk.core.refactoring.RefactoringStatus;
+
+import java.util.Map;
+
+/**
+ * Partial implementation of a Dart refactoring contribution.
+ * <p>
+ * Note: this class is not intended to be extended outside the refactoring framework.
+ * </p>
+ */
+public abstract class DartRefactoringContribution extends RefactoringContribution {
+
+  /**
+   * Creates the a new refactoring instance.
+   * 
+   * @param descriptor the refactoring descriptor
+   * @param status the status used for the resulting status
+   * @return the refactoring, or <code>null</code>
+   * @throws CoreException if an error occurs while creating the refactoring
+   */
+  public abstract Refactoring createRefactoring(DartRefactoringDescriptor descriptor,
+      RefactoringStatus status) throws CoreException;
+
+  @Override
+  @SuppressWarnings("unchecked")
+  public final Map<String, String> retrieveArgumentMap(final RefactoringDescriptor descriptor) {
+    Assert.isNotNull(descriptor);
+    if (descriptor instanceof DartRefactoringDescriptor) {
+      return ((DartRefactoringDescriptor) descriptor).getArguments();
+    }
+    return super.retrieveArgumentMap(descriptor);
+  }
+}