Issue 61: Provide an extension point to have custom local file -> script mapping

plugins/org.chromium.debug.core/src/org/chromium/debug/core/ReverseLookupContainer.java

Index: plugins/org.chromium.debug.core/src/org/chromium/debug/core/ReverseLookupContainer.java
diff --git a/plugins/org.chromium.debug.core/src/org/chromium/debug/core/ReverseLookupContainer.java b/plugins/org.chromium.debug.core/src/org/chromium/debug/core/ReverseLookupContainer.java
new file mode 100644
index 0000000000000000000000000000000000000000..2632a225773859b4a39c7207ff502e689ca2b3c3
--- /dev/null
+++ b/plugins/org.chromium.debug.core/src/org/chromium/debug/core/ReverseLookupContainer.java
@@ -0,0 +1,46 @@
+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.debug.core;
+
+import org.eclipse.debug.core.sourcelookup.ISourceContainer;
+
+/**
+ * A kind of source container that explicitly supports reverse look-up, i.e. mapping
+ * from a source file to element name.
+ * Custom container implementation may also implement this interface.
+ * <p>This interface is used in {@link ReverseSourceLookup} class. The class also provides
+ * reverse look-up for certain standard containers.
+ * <p>Possible downcasting {@link ISourceContainer} to {@link ReverseLookupContainer} is a regular
+ * operation. Since raw "instanceof" is considered anti-typesafe operation, it was incapsulated in
+ * {@link Cast} class.
+ */
+public interface ReverseLookupContainer extends ISourceContainer {
+  /**
+   * Returns a container wrapper instance that will be used for actual look-up. This method
+   * may also be called from UI to check whether container is properly configured for reverse
+   * look-up. The return object is considered light-weight and the method is called
+   * for each look-up.
+   * <p>
+   * If container has inner containers, it is supposed to prepare similar wrapper for them
+   * by calling {@link ReverseSourceLookup#wrapSourceContainer} method.
+   *
+   * @return a container wrapper instance or null if reverse look-up is not (currently) available
+   */
+  ReverseSourceLookup.ContainerWrapper getReveseLookupImpl();
+
+  /**
+   * A utility class that legalizes one particular downcast. Manual instanceof/cast operations are
+   * discouraged, because they are not declared and thus not type-safe.
+   */
+  class Cast {
+    public static ReverseLookupContainer fromContainer(ISourceContainer sourceContainer) {
+      if (sourceContainer instanceof ReverseLookupContainer) {
+        return (ReverseLookupContainer) sourceContainer;
+      } else {
+        return null;
+      }
+    }
+  }
+}