[CacheStorage] Give ownership of all CacheStorageCaches to CacheStorage

content/browser/cache_storage/cache_storage_cache_handle.h

+// Copyright 2016 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 CONTENT_BROWSER_CACHE_STORAGE_CACHE_STORAGE_CACHE_HANDLE_H_
+#define CONTENT_BROWSER_CACHE_STORAGE_CACHE_STORAGE_CACHE_HANDLE_H_
+
+#include "base/memory/weak_ptr.h"
+#include "content/browser/cache_storage/cache_storage.h"
+#include "content/browser/cache_storage/cache_storage_cache.h"
+
+namespace content {
+
+// Holds a reference to a CacheStorageCache. The CacheStorage will keep the
+// CacheStorageCache alive until the last handle is destroyed or the
+// CacheStorage is deleted.
+class CONTENT_EXPORT CacheStorageCacheHandle {
+ public:
+  ~CacheStorageCacheHandle();
+
+  // Returns the underlying CacheStorageCache*. Will return nullptr if the
+  // CacheStorage has been deleted.
+  CacheStorageCache* value() { return cache_storage_cache_.get(); }
+
+  std::unique_ptr<CacheStorageCacheHandle> Clone();
+
+ private:
+  friend class CacheStorage;
+
+  CacheStorageCacheHandle(base::WeakPtr<CacheStorageCache> cache_storage_cache,
+                          base::WeakPtr<CacheStorage> cache_storage);
+
+  base::WeakPtr<CacheStorageCache> cache_storage_cache_;
+  base::WeakPtr<CacheStorage> cache_storage_;
+
+  DISALLOW_COPY_AND_ASSIGN(CacheStorageCacheHandle);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_CACHE_STORAGE_CACHE_STORAGE_CACHE_HANDLE_H_