Fix NPE in UsageStats for new User

Bug:16946585

Change-Id: Ibd0d674681f3f49087305cea33ce7292f5d2229d

Author: Adam Lesinski

services/usage/java/com/android/server/usage/UsageStatsService.java

@@ -311,11 +311,15 @@ public ParceledListSlice<UsageStats> queryUsageStats(int bucketType, long beginT
             final int userId = UserHandle.getCallingUserId();
             final long token = Binder.clearCallingIdentity();
             try {
-                return new ParceledListSlice<>(UsageStatsService.this.queryUsageStats(
-                        userId, bucketType, beginTime, endTime));
+                final List<UsageStats> results = UsageStatsService.this.queryUsageStats(
+                        userId, bucketType, beginTime, endTime);
+                if (results != null) {
+                    return new ParceledListSlice<>(results);
+                }
             } finally {
                 Binder.restoreCallingIdentity(token);
             }
+            return null;
         }
 
         @Override

services/usage/java/com/android/server/usage/UserUsageStatsService.java

@@ -181,7 +181,7 @@ List<UsageStats> queryUsageStats(int bucketType, long beginTime, long endTime) {
 
         final List<UsageStats> results = mDatabase.queryUsageStats(bucketType, beginTime, endTime);
         if (DEBUG) {
-            Slog.d(TAG, mLogPrefix + "Results: " + results.size());
+            Slog.d(TAG, mLogPrefix + "Results: " + (results == null ? 0 : results.size()));
         }
         return results;
     }