Make SimpleEntryImpl ref counted.

net/disk_cache/simple/simple_backend_impl.h

Index: net/disk_cache/simple/simple_backend_impl.h
diff --git a/net/disk_cache/simple/simple_backend_impl.h b/net/disk_cache/simple/simple_backend_impl.h
index fd5c53a936cc938754acd42c74edd08487ec1c1b..ccb4e73377557d1a7326a467af066301b70f9ca0 100644
--- a/net/disk_cache/simple/simple_backend_impl.h
+++ b/net/disk_cache/simple/simple_backend_impl.h
@@ -11,6 +11,7 @@
 
 #include "base/compiler_specific.h"
 #include "base/files/file_path.h"
+#include "base/memory/ref_counted.h"
 #include "base/task_runner.h"
 #include "net/base/cache_type.h"
 #include "net/disk_cache/disk_cache.h"
@@ -79,7 +80,7 @@ class NET_EXPORT_PRIVATE SimpleBackendImpl : public Backend {
       const InitializeIndexCallback& initialize_index_callback);
 
   const base::FilePath path_;
-  scoped_ptr<SimpleIndex> index_;
+  scoped_refptr<SimpleIndex> index_;
   const scoped_refptr<base::TaskRunner> cache_thread_;
 };