Log when /cache files are deleted.

Bug: 6362988
Change-Id: Ib8497453c45612be5b83035eeaf3abe6d716ccbf

services/java/com/android/server/DeviceStorageMonitorService.java

@@ -26,6 +26,7 @@ import android.content.pm.IPackageDataObserver;
 import android.content.pm.IPackageManager;
 import android.os.Binder;
 import android.os.Environment;
+import android.os.FileObserver;
 import android.os.Handler;
 import android.os.Message;
 import android.os.Process;
@@ -91,6 +92,7 @@ public class DeviceStorageMonitorService extends Binder {
     private Intent mStorageFullIntent;
     private Intent mStorageNotFullIntent;
     private CachePackageDataObserver mClearCacheObserver;
+    private final CacheFileDeletedObserver mCacheFileDeletedObserver;
     private static final int _TRUE = 1;
     private static final int _FALSE = 0;
     private long mMemLowThreshold;
@@ -324,6 +326,9 @@ public class DeviceStorageMonitorService extends Binder {
         mMemLowThreshold = getMemThreshold();
         mMemFullThreshold = getMemFullThreshold();
         checkMemory(true);
+
+        mCacheFileDeletedObserver = new CacheFileDeletedObserver();
+        mCacheFileDeletedObserver.startWatching();
     }
 
 
@@ -419,4 +424,15 @@ public class DeviceStorageMonitorService extends Binder {
     public boolean isMemoryLow() {
         return mLowMemFlag;
     }
+
+    public static class CacheFileDeletedObserver extends FileObserver {
+        public CacheFileDeletedObserver() {
+            super(Environment.getDownloadCacheDirectory().getAbsolutePath(), FileObserver.DELETE);
+        }
+
+        @Override
+        public void onEvent(int event, String path) {
+            EventLogTags.writeCacheFileDeleted(path);
+        }
+    }
 }

services/java/com/android/server/EventLogTags.logtags

@@ -36,7 +36,7 @@ option java_package com.android.server
 
 
 # ---------------------------
-# DeviceStorageMonitoryService.java
+# DeviceStorageMonitorService.java
 # ---------------------------
 # The disk space free on the /data partition, in bytes
 2744 free_storage_changed (data|2|2)
@@ -44,6 +44,8 @@ option java_package com.android.server
 2745 low_storage (data|2|2)
 # disk space free on the /data, /system, and /cache partitions in bytes
 2746 free_storage_left (data|2|2),(system|2|2),(cache|2|2)
+# file on cache partition was deleted
+2748 cache_file_deleted (path|3)
 
 
 # ---------------------------