Do not disturb: persist user config.

Load and store user configuration for do not disturb.  Separate
out service-related aspects into new helper.  Make config availble
over NoMan for settings.

Implement phone + message based filtering (package whitelist for now).

Implement automatic enter/exit zen mode overnight scheduler.

Bug:14211946
Change-Id: Ib28aab0e4c5c9a5fd0b950b2884b1ab618fdfeca
diff --git a/core/java/android/provider/Settings.java b/core/java/android/provider/Settings.java
index 1e202ca..2ce6210 100644
--- a/core/java/android/provider/Settings.java
+++ b/core/java/android/provider/Settings.java
@@ -6120,6 +6120,13 @@
         }
 
         /**
+         * Opaque value, changes when persisted zen mode configuration changes.
+         *
+         * @hide
+         */
+        public static final String ZEN_MODE_CONFIG_ETAG = "zen_mode_config_etag";
+
+        /**
          * Defines global heads up toggle.  One of HEADS_UP_OFF, HEADS_UP_ON.
          *
          * @hide