move event log tags used by system server into this package

We can now locate event log tag definitions in individual packages
(and java constants for the tag numbers get auto-generated), so move
all the tags used by the system server into the package.
diff --git a/services/java/com/android/server/DeviceStorageMonitorService.java b/services/java/com/android/server/DeviceStorageMonitorService.java
index 57af029..8e54c6e 100644
--- a/services/java/com/android/server/DeviceStorageMonitorService.java
+++ b/services/java/com/android/server/DeviceStorageMonitorService.java
@@ -63,9 +63,6 @@
     private static final int LOW_MEMORY_NOTIFICATION_ID = 1;
     private static final int DEFAULT_THRESHOLD_PERCENTAGE = 10;
     private static final int DEFAULT_FREE_STORAGE_LOG_INTERVAL_IN_MINUTES = 12*60; //in minutes
-    private static final int EVENT_LOG_STORAGE_BELOW_THRESHOLD = 2744;
-    private static final int EVENT_LOG_LOW_STORAGE_NOTIFICATION = 2745;
-    private static final int EVENT_LOG_FREE_STORAGE_LEFT = 2746;
     private static final long DEFAULT_DISK_FREE_CHANGE_REPORTING_THRESHOLD = 2 * 1024 * 1024; // 2MB
     private static final long DEFAULT_CHECK_INTERVAL = MONITOR_INTERVAL*60*1000;
     private long mFreeMem;  // on /data
@@ -159,7 +156,7 @@
                 // ignore; report -1
             }
             mCacheFileStats.restat(CACHE_PATH);
-            EventLog.writeEvent(EVENT_LOG_FREE_STORAGE_LEFT,
+            EventLog.writeEvent(EventLogTags.FREE_STORAGE_LEFT,
                                 mFreeMem, mFreeSystem, mFreeCache);
         }
         // Read the reporting threshold from Gservices
@@ -170,7 +167,7 @@
         long delta = mFreeMem - mLastReportedFreeMem;
         if (delta > threshold || delta < -threshold) {
             mLastReportedFreeMem = mFreeMem;
-            EventLog.writeEvent(EVENT_LOG_STORAGE_BELOW_THRESHOLD, mFreeMem);
+            EventLog.writeEvent(EventLogTags.FREE_STORAGE_CHANGED, mFreeMem);
         }
     }
 
@@ -292,7 +289,7 @@
     private final void sendNotification() {
         if(localLOGV) Log.i(TAG, "Sending low memory notification");
         //log the event to event log with the amount of free storage(in bytes) left on the device
-        EventLog.writeEvent(EVENT_LOG_LOW_STORAGE_NOTIFICATION, mFreeMem);
+        EventLog.writeEvent(EventLogTags.LOW_STORAGE, mFreeMem);
         //  Pack up the values and broadcast them to everyone
         Intent lowMemIntent = new Intent(Intent.ACTION_MANAGE_PACKAGE_STORAGE);
         lowMemIntent.putExtra("memory", mFreeMem);