Make DEBUG_FPS_DIVISOR updatable via setting for possible experiments

Bug: 70982379
Test: Manual test with "settings put global fps_divisor 4" and reboot

Change-Id: I61437ede907fc387257bf9c07dab46f0032d4e1b
diff --git a/core/java/android/provider/Settings.java b/core/java/android/provider/Settings.java
index 850aedd..ce35d16 100644
--- a/core/java/android/provider/Settings.java
+++ b/core/java/android/provider/Settings.java
@@ -9664,6 +9664,14 @@
         public static final String SYS_VDSO = "sys_vdso";
 
         /**
+         * An integer to reduce the FPS by this factor. Only for experiments. Need to reboot the
+         * device for this setting to take full effect.
+         *
+         * @hide
+         */
+        public static final String FPS_DEVISOR = "fps_divisor";
+
+        /**
          * App standby (app idle) specific settings.
          * This is encoded as a key=value list, separated by commas. Ex:
          * <p>
diff --git a/core/tests/coretests/src/android/provider/SettingsBackupTest.java b/core/tests/coretests/src/android/provider/SettingsBackupTest.java
index 410bee0..af668bd 100644
--- a/core/tests/coretests/src/android/provider/SettingsBackupTest.java
+++ b/core/tests/coretests/src/android/provider/SettingsBackupTest.java
@@ -351,6 +351,7 @@
                     Settings.Global.SYS_STORAGE_THRESHOLD_MAX_BYTES,
                     Settings.Global.SYS_STORAGE_THRESHOLD_PERCENTAGE,
                     Settings.Global.SYS_VDSO,
+                    Settings.Global.FPS_DEVISOR,
                     Settings.Global.TCP_DEFAULT_INIT_RWND,
                     Settings.Global.TETHER_DUN_APN,
                     Settings.Global.TETHER_DUN_REQUIRED,