Zen: Implement calendar event system condition provider.

 - Wire up basic implementation for the system provider that
   handles event-based DND subscriptions.
 - Backed by the standard system calendar content provider.
 - Move shared time utils to base class, clean up logging.

Bug: 20064962
Change-Id: I070b6baa580c592c2ab4101c6b44a254787f9dd7
diff --git a/services/core/java/com/android/server/notification/ConditionProviders.java b/services/core/java/com/android/server/notification/ConditionProviders.java
index b36fcd2..8c6afaf 100644
--- a/services/core/java/com/android/server/notification/ConditionProviders.java
+++ b/services/core/java/com/android/server/notification/ConditionProviders.java
@@ -121,6 +121,9 @@
     @Override
     public void onBootPhaseAppsCanStart() {
         super.onBootPhaseAppsCanStart();
+        for (int i = 0; i < mSystemConditionProviders.size(); i++) {
+            mSystemConditionProviders.valueAt(i).onBootComplete();
+        }
         if (mCallback != null) {
             mCallback.onBootComplete();
         }