Doze: Add a user opt-out setting.

When devices are configured with a doze component, the user
now has the option of disabling doze mode with a secure setting.

Bug:16703536
Change-Id: Ieab6ee8d2acf54580b86fb16e9d77b52080fb3b1
diff --git a/core/java/android/provider/Settings.java b/core/java/android/provider/Settings.java
index 5d5be4a..4b7e615 100644
--- a/core/java/android/provider/Settings.java
+++ b/core/java/android/provider/Settings.java
@@ -4607,6 +4607,12 @@
         public static final String WAKE_GESTURE_ENABLED = "wake_gesture_enabled";
 
         /**
+         * Whether the device should doze if configured.
+         * @hide
+         */
+        public static final String DOZE_ENABLED = "doze_enabled";
+
+        /**
          * The current night mode that has been selected by the user.  Owned
          * and controlled by UiModeManagerService.  Constants are as per
          * UiModeManager.