Autofill sample: use AppCompatActivity for AuthActivity.

Bug: 38182790
Test: manual
Change-Id: Ie0133dc9ca1386d08296e9f2e4be653665df3900
diff --git a/input/autofill/AutofillFramework/Application/src/main/java/com/example/android/autofillframework/multidatasetservice/AuthActivity.java b/input/autofill/AutofillFramework/Application/src/main/java/com/example/android/autofillframework/multidatasetservice/AuthActivity.java
index c365cc3..c6615ff 100644
--- a/input/autofill/AutofillFramework/Application/src/main/java/com/example/android/autofillframework/multidatasetservice/AuthActivity.java
+++ b/input/autofill/AutofillFramework/Application/src/main/java/com/example/android/autofillframework/multidatasetservice/AuthActivity.java
@@ -25,6 +25,7 @@
 import android.service.autofill.Dataset;
 import android.service.autofill.FillResponse;
 import android.support.annotation.Nullable;
+import android.support.v7.app.AppCompatActivity;
 import android.text.Editable;
 import android.util.Log;
 import android.view.View;
@@ -50,7 +51,7 @@
  * It is launched when an Autofill Response or specific Dataset within the Response requires
  * authentication to access. It bundles the result in an Intent.
  */
-public class AuthActivity extends Activity {
+public class AuthActivity extends AppCompatActivity {
 
     // Unique id for dataset intents.
     private static int sDatasetPendingIntentId = 0;