Add @TestApi to ActivityOptions.setLaunchStackId

Bug: 28506739
Change-Id: I20fe4d080c125b38a84d9832a497340f805e82e7
diff --git a/api/test-current.txt b/api/test-current.txt
index 8764333..f4d32e0 100644
--- a/api/test-current.txt
+++ b/api/test-current.txt
@@ -3869,6 +3869,7 @@
     method public static android.app.ActivityOptions makeThumbnailScaleUpAnimation(android.view.View, android.graphics.Bitmap, int, int);
     method public void requestUsageTimeReport(android.app.PendingIntent);
     method public android.app.ActivityOptions setLaunchBounds(android.graphics.Rect);
+    method public void setLaunchStackId(int);
     method public android.os.Bundle toBundle();
     method public void update(android.app.ActivityOptions);
     field public static final java.lang.String EXTRA_USAGE_TIME_REPORT = "android.activity.usage_time";
diff --git a/core/java/android/app/ActivityOptions.java b/core/java/android/app/ActivityOptions.java
index 051295e..a30f629 100644
--- a/core/java/android/app/ActivityOptions.java
+++ b/core/java/android/app/ActivityOptions.java
@@ -20,6 +20,7 @@
 import static android.app.ActivityManager.StackId.INVALID_STACK_ID;
 
 import android.annotation.Nullable;
+import android.annotation.TestApi;
 import android.content.Context;
 import android.content.Intent;
 import android.graphics.Bitmap;
@@ -939,6 +940,7 @@
     }
 
     /** @hide */
+    @TestApi
     public void setLaunchStackId(int launchStackId) {
         mLaunchStackId = launchStackId;
     }