Secure FRP : Remove @SystemApi annotation.

Bug: 141262900
Bug: 150699478
Test: NA. Api change only.

Change-Id: I329455e8379041cfe6f85c09d9a23ac7d1af27af

api/current.txt

@@ -40716,6 +40716,7 @@ package android.provider {
     field public static final String PARENTAL_CONTROL_LAST_UPDATE = "parental_control_last_update";
     field public static final String PARENTAL_CONTROL_REDIRECT_URL = "parental_control_redirect_url";
     field public static final String RTT_CALLING_MODE = "rtt_calling_mode";
+    field public static final String SECURE_FRP_MODE = "secure_frp_mode";
     field public static final String SELECTED_INPUT_METHOD_SUBTYPE = "selected_input_method_subtype";
     field public static final String SETTINGS_CLASSNAME = "settings_classname";
     field public static final String SKIP_FIRST_USE_HINTS = "skip_first_use_hints";

api/system-current.txt

@@ -9379,7 +9379,6 @@ package android.provider {
     field public static final String LOCK_SCREEN_ALLOW_PRIVATE_NOTIFICATIONS = "lock_screen_allow_private_notifications";
     field public static final String LOCK_SCREEN_SHOW_NOTIFICATIONS = "lock_screen_show_notifications";
     field public static final String ODI_CAPTIONS_ENABLED = "odi_captions_enabled";
-    field public static final String SECURE_FRP_MODE = "secure_frp_mode";
     field public static final String THEME_CUSTOMIZATION_OVERLAY_PACKAGES = "theme_customization_overlay_packages";
     field public static final String USER_SETUP_COMPLETE = "user_setup_complete";
     field public static final int USER_SETUP_PERSONALIZATION_COMPLETE = 10; // 0xa

core/java/android/provider/Settings.java

@@ -6090,10 +6090,7 @@ public final class Settings {
          * device is removed from this mode.
          * <p>
          * Type: int (0 for false, 1 for true)
-         *
-         * @hide
          */
-        @SystemApi
         public static final String SECURE_FRP_MODE = "secure_frp_mode";
 
         /**