Mark MultiDexTestRunner as deprecated

Bug: 35796382
Test: N/A
Change-Id: I7a36e9223b010a04a1d2ea28914d0b502dd7f61e
diff --git a/instrumentation/src/com/android/test/runner/MultiDexTestRunner.java b/instrumentation/src/com/android/test/runner/MultiDexTestRunner.java
index f56b53f..3de3632 100644
--- a/instrumentation/src/com/android/test/runner/MultiDexTestRunner.java
+++ b/instrumentation/src/com/android/test/runner/MultiDexTestRunner.java
@@ -22,6 +22,11 @@
 
 /**
  * {@link android.test.InstrumentationTestRunner} for testing application needing multidex support.
+ *
+ * @deprecated Use
+ * <a href="{@docRoot}reference/android/support/test/runner/AndroidJUnitRunner.html">
+ * AndroidJUnitRunner</a> instead. New tests should be written using the
+ * <a href="{@docRoot}tools/testing-support-library/index.html">Android Testing Support Library</a>.
  */
 public class MultiDexTestRunner extends InstrumentationTestRunner {