Write out CacheStorageCache size to index file.

content/browser/cache_storage/cache_storage_cache_observer.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_OBSERVER_H_
+#define CONTENT_BROWSER_CACHE_STORAGE_CACHE_STORAGE_CACHE_OBSERVER_H_
+
+#include "content/common/content_export.h"
+
+namespace content {
+
+class CacheStorageCache;
+
+class CONTENT_EXPORT CacheStorageCacheObserver {
+ public:
+  // SET: The cache size has been set to the absolute size.
+  // DELTA: The cache size has changed by the specified amount.
+  enum class Whence { SET, DELTA };
+
+  // The cache size has changed.
+  virtual void CacheSizeSet(const CacheStorageCache* cache,
+                            Whence whence,
+                            int64_t size) = 0;
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_CACHE_STORAGE_CACHE_STORAGE_CACHE_OBSERVER_H_