Get rid of custom negaitve save button label

Removed the ability for an autofill provider to set
a custom string for the negative button. Also make
the old hidden APIs non-abstract to avoid runime
crashes for unimplemented methods.

Test: CtsAutoFillServiceTestCases pass

bug:37649790

Change-Id: If776d26de48382eeb064bdead5d4d5fdb0ff2e7e
diff --git a/core/java/android/service/autofill/AutofillService.java b/core/java/android/service/autofill/AutofillService.java
index edb9098..32b078f 100644
--- a/core/java/android/service/autofill/AutofillService.java
+++ b/core/java/android/service/autofill/AutofillService.java
@@ -223,9 +223,11 @@
      * @hide
      */
     @Deprecated
-    public abstract void onFillRequest(@NonNull AssistStructure structure, @Nullable Bundle data,
+    public void onFillRequest(@NonNull AssistStructure structure, @Nullable Bundle data,
             int flags, @NonNull CancellationSignal cancellationSignal,
-            @NonNull FillCallback callback);
+            @NonNull FillCallback callback) {
+
+    }
 
     /**
      * Called when user requests service to save the fields of an {@link Activity}.
@@ -260,8 +262,10 @@
      * @hide
      */
     @Deprecated
-    public abstract void onSaveRequest(@NonNull AssistStructure structure, @Nullable Bundle data,
-            @NonNull SaveCallback callback);
+    public void onSaveRequest(@NonNull AssistStructure structure, @Nullable Bundle data,
+            @NonNull SaveCallback callback) {
+
+    }
 
     /**
      * Called when the Android system disconnects from the service.