fix bug 5942522

Change-Id: Ice16e63b42d5e8c89994d0844f62adaefc8a92a1
diff --git a/graphics/java/android/graphics/drawable/AnimationDrawable.java b/graphics/java/android/graphics/drawable/AnimationDrawable.java
index 07de074..35343be 100644
--- a/graphics/java/android/graphics/drawable/AnimationDrawable.java
+++ b/graphics/java/android/graphics/drawable/AnimationDrawable.java
@@ -102,7 +102,12 @@
 
     /**
      * <p>Starts the animation, looping if necessary. This method has no effect
-     * if the animation is running.</p>
+     * if the animation is running. Do not call this in the {@link android.app.Activity#onCreate}
+     * method of your activity, because the {@link android.graphics.drawable.AnimationDrawable} is
+     * not yet fully attached to the window. If you want to play
+     * the animation immediately, without requiring interaction, then you might want to call it
+     * from the {@link android.app.Activity#onWindowFocusChanged} method in your activity,
+     * which will get called when Android brings your window into focus.</p>
      *
      * @see #isRunning()
      * @see #stop()