[CacheStorage] Temporarily preserve recently opened caches from CacheStorageDispatcherHost

content/browser/cache_storage/cache_storage_dispatcher_host.h

 // Copyright 2015 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_DISPATCHER_HOST_H_
 #define CONTENT_BROWSER_CACHE_STORAGE_CACHE_STORAGE_DISPATCHER_HOST_H_
 
 #include <stdint.h>
 
 #include <list>
@@ skipping 137 matching lines @@
       int request_id,
       std::unique_ptr<CacheStorageCacheHandle> cache_handle,
       CacheStorageError error,
       std::unique_ptr<CacheStorageCache::Requests> requests);
   void OnCacheBatchCallback(
       int thread_id,
       int request_id,
       std::unique_ptr<CacheStorageCacheHandle> cache_handle,
       CacheStorageError error);
 
+  void StopPreservingCache(const CacheStorageCache* cache);
+
   // Hangs onto a cache handle. Returns a unique cache_id. Call
   // DropCacheReference when the reference is no longer needed.
   CacheID StoreCacheReference(
       std::unique_ptr<CacheStorageCacheHandle> cache_handle);
   void DropCacheReference(CacheID cache_id);
 
   // Stores blob handles while waiting for acknowledgement of receipt from the
   // renderer.
   void StoreBlobDataHandle(const storage::BlobDataHandle& blob_data_handle);
   void DropBlobDataHandle(const std::string& uuid);
 
+  // Store handles to recently opened caches for a short period in case they're
+  // used again in the near future.
+  std::map<const CacheStorageCache*, std::unique_ptr<CacheStorageCacheHandle>>
+      preserved_cache_handles_;
+
   IDToCacheMap id_to_cache_map_;
   CacheID next_cache_id_ = 0;
 
   UUIDToBlobDataHandleList blob_handle_store_;
 
   scoped_refptr<CacheStorageContextImpl> context_;
 
+  base::WeakPtrFactory<CacheStorageDispatcherHost> weak_ptr_factory_;

[nhiroki, 2016/06/28 06:22:34]

Is this usage of WeakPtrFactory safe?

According to this discussion, having WeakPtr to RefCountedThreadSafe object
(CacheStorageDispatcherHost inherits BrowserMessageFilter that is
RefCountedThreadSafe) seems to be quite controversial:
https://groups.google.com/a/google.com/forum/?utm_medium=email&utm_source=foo...

[jkarlin, 2016/06/28 11:20:14]

Thanks, and good point. Fixed.

+
   DISALLOW_COPY_AND_ASSIGN(CacheStorageDispatcherHost);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_CACHE_STORAGE_CACHE_STORAGE_DISPATCHER_HOST_H_