Return builder from addOutputInspection

Change-Id: I8a31a073bdfc8178ca0b50c9cd27807c099890e2
diff --git a/src/main/java/com/android/tools/r8/BaseCompilerCommand.java b/src/main/java/com/android/tools/r8/BaseCompilerCommand.java
index b12b467..f0cb3e8 100644
--- a/src/main/java/com/android/tools/r8/BaseCompilerCommand.java
+++ b/src/main/java/com/android/tools/r8/BaseCompilerCommand.java
@@ -618,8 +618,9 @@
      *
      * @param inspection Inspection callback receiving inspectors denoting parts of the output.
      */
-    public void addOutputInspection(Consumer<Inspector> inspection) {
+    public B addOutputInspection(Consumer<Inspector> inspection) {
       outputInspections.add(inspection);
+      return self();
     }
 
     List<Consumer<Inspector>> getOutputInspections() {