[CacheStorage] Temporarily preserve recently opened caches from CacheStorageDispatcherHost

content/browser/cache_storage/cache_storage_dispatcher_host.h

Index: content/browser/cache_storage/cache_storage_dispatcher_host.h
diff --git a/content/browser/cache_storage/cache_storage_dispatcher_host.h b/content/browser/cache_storage/cache_storage_dispatcher_host.h
index d937bac03486e5343e5a002e939dcf5575774754..f3dce4ffe834d876b1517e03a7788ac1aeb8d117 100644
--- a/content/browser/cache_storage/cache_storage_dispatcher_host.h
+++ b/content/browser/cache_storage/cache_storage_dispatcher_host.h
@@ -155,6 +155,8 @@ class CONTENT_EXPORT CacheStorageDispatcherHost : public BrowserMessageFilter {
       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(
@@ -166,6 +168,11 @@ class CONTENT_EXPORT CacheStorageDispatcherHost : public BrowserMessageFilter {
   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;
 
@@ -173,6 +180,8 @@ class CONTENT_EXPORT CacheStorageDispatcherHost : public BrowserMessageFilter {
 
   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);
 };