move backstage_power_flags_lib to framework flag list

This change makes backstage_power_flags_lib visible to metalava so
metalava won't hide the guarded api.

Since the guarded api are in the framework, this change move this flag
to framework flag list.

Bug: 333995906
Test: lunch sdk-next-eng && m sdk dist and presubmit
Change-Id: Id21ae3029a2201a879e53248de2a5c5e6a969ec7

AconfigFlags.bp

@@ -74,6 +74,7 @@ aconfig_declarations_group {
         "android.view.inputmethod.flags-aconfig-java",
         "android.webkit.flags-aconfig-java",
         "android.widget.flags-aconfig-java",
+        "backstage_power_flags_lib",
         "backup_flags_lib",
         "camera_platform_flags_core_java_lib",
         "com.android.hardware.input-aconfig-java",
@@ -1333,3 +1334,20 @@ java_aconfig_library {
     aconfig_declarations: "android.systemserver.flags-aconfig",
     defaults: ["framework-minus-apex-aconfig-java-defaults"],
 }
+
+// backstage power
+aconfig_declarations {
+    name: "backstage_power_flags",
+    package: "com.android.server.power.optimization",
+    container: "system",
+    exportable: true,
+    srcs: [
+        "services/core/java/com/android/server/power/stats/flags.aconfig",
+    ],
+}
+
+java_aconfig_library {
+    name: "backstage_power_flags_lib",
+    aconfig_declarations: "backstage_power_flags",
+    defaults: ["framework-minus-apex-aconfig-java-defaults"],
+}

services/core/Android.bp

@@ -243,7 +243,6 @@ java_library_static {
         "com.android.sysprop.watchdog",
         "securebox",
         "apache-commons-math",
-        "backstage_power_flags_lib",
         "notification_flags_lib",
         "power_hint_flags_lib",
         "biometrics_flags_lib",

services/core/java/com/android/server/power/Android.bp

-aconfig_declarations {
-    name: "backstage_power_flags",
-    package: "com.android.server.power.optimization",
-    container: "system",
-    srcs: [
-        "stats/*.aconfig",
-    ],
-}
-
-java_aconfig_library {
-    name: "backstage_power_flags_lib",
-    aconfig_declarations: "backstage_power_flags",
-    sdk_version: "system_current",
-}