Virtual destructors should have virtual keyword.

net/disk_cache/file_lock.h

Index: net/disk_cache/file_lock.h
diff --git a/net/disk_cache/file_lock.h b/net/disk_cache/file_lock.h
index 48f872ac6f914aae6d48b14d639ea73f6e558390..9823292816ae9d735375ac41f2274d7e05c746f1 100644
--- a/net/disk_cache/file_lock.h
+++ b/net/disk_cache/file_lock.h
@@ -31,9 +31,8 @@ namespace disk_cache {
 class NET_TEST FileLock {
  public:
   explicit FileLock(BlockFileHeader* header);
-  virtual ~FileLock() {
-    Unlock();
-  }
+  virtual ~FileLock();
+
   // Virtual to make sure the compiler never inlines the calls.
   virtual void Lock();
   virtual void Unlock();