Code quality and standards in SimpleBackend.

net/disk_cache/simple/simple_backend_impl.h

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef NET_DISK_CACHE_SIMPLE_SIMPLE_BACKEND_IMPL_H_
 #define NET_DISK_CACHE_SIMPLE_SIMPLE_BACKEND_IMPL_H_
 
 #include <string>
 #include <utility>
 #include <vector>
 
 #include "base/compiler_specific.h"
 #include "base/files/file_path.h"
 #include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
 #include "base/task_runner.h"
 #include "net/base/cache_type.h"
 #include "net/disk_cache/disk_cache.h"
-#include "net/disk_cache/simple/simple_index.h"
 
 namespace base {
-class MessageLoopProxy;
+class SingleThreadTaskRunner;
 }
 
 namespace disk_cache {
 
 // SimpleBackendImpl is a new cache backend that stores entries in individual
 // files.
 
 // It is currently a work in progress, missing many features of a real cache,
 // such as eviction.
 
 // See http://www.chromium.org/developers/design-documents/network-stack/disk-cache/very-simple-backend
 
+class SimpleIndex;
+
 class NET_EXPORT_PRIVATE SimpleBackendImpl : public Backend {
  public:
   SimpleBackendImpl(const base::FilePath& path, int max_bytes,
                     net::CacheType type,
-                    const scoped_refptr<base::TaskRunner>& cache_thread,
+                    base::SingleThreadTaskRunner* cache_thread,
                     net::NetLog* net_log);
 
   virtual ~SimpleBackendImpl();
 
   // Must run on IO Thread.
   int Init(const CompletionCallback& completion_callback);
 
   // From Backend:
   virtual net::CacheType GetCacheType() const OVERRIDE;
   virtual int32 GetEntryCount() const OVERRIDE;
@@ skipping 18 matching lines @@
 
  private:
   typedef base::Callback<void(int result)> InitializeIndexCallback;
 
   // Must run on IO Thread.
   void InitializeIndex(const CompletionCallback& callback, int result);
 
   // Try to create the directory if it doesn't exist.
   // Must run on Cache Thread.
   static void CreateDirectory(
-      base::MessageLoopProxy* io_thread,
+      base::SingleThreadTaskRunner* io_thread,
       const base::FilePath& path,
       const InitializeIndexCallback& initialize_index_callback);
 
   const base::FilePath path_;
-  scoped_refptr<SimpleIndex> index_;
-  const scoped_refptr<base::TaskRunner> cache_thread_;
+  scoped_ptr<SimpleIndex> index_;
+  const scoped_refptr<base::SingleThreadTaskRunner> cache_thread_;
 };
 
 }  // namespace disk_cache
 
 #endif  // NET_DISK_CACHE_SIMPLE_SIMPLE_BACKEND_IMPL_H_