[BlobAsync] Disk support for blob storage

storage/browser/blob/blob_storage_registry.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 STORAGE_BROWSER_BLOB_BLOB_STORAGE_REGISTRY_H_
 #define STORAGE_BROWSER_BLOB_BLOB_STORAGE_REGISTRY_H_
 
 #include <stddef.h>
 
 #include <map>
 #include <memory>
 #include <string>
 #include <vector>
 
 #include "base/callback_forward.h"
 #include "base/containers/scoped_ptr_hash_map.h"
 #include "base/macros.h"
+#include "base/optional.h"
 #include "storage/browser/blob/internal_blob_data.h"
 #include "storage/browser/storage_browser_export.h"
 #include "storage/common/blob_storage/blob_storage_constants.h"
 
 class GURL;
 
 namespace storage {
+class BlobDataHandle;
+class InternalBlobData;
+class ShareableBlobDataItem;
 
 // This class stores the blob data in the various states of construction, as
 // well as URL mappings to blob uuids.
 // Implementation notes:
 // * There is no implicit refcounting in this class, except for setting the
 //   refcount to 1 on registration.
 // * When removing a uuid registration, we do not check for URL mappings to that
 //   uuid. The user must keep track of these.
 class STORAGE_EXPORT BlobStorageRegistry {
  public:
-  // True means the blob was constructed successfully, and false means that
-  // there was an error, which is reported in the second argument.
-  using BlobConstructedCallback =
-      base::Callback<void(bool, IPCBlobCreationCancelCode)>;
-
-  enum class BlobState {
-    // The blob is pending transportation from the renderer. This is the default
-    // state on entry construction.
-    PENDING,
-    // The blob is complete and can be read from.
-    COMPLETE,
-    // The blob is broken and no longer holds data. This happens when there was
-    // a problem constructing the blob, or we've run out of memory.
-    BROKEN
-  };
-
-  struct STORAGE_EXPORT Entry {
-    size_t refcount;
-    BlobState state;
-    std::vector<BlobConstructedCallback> build_completion_callbacks;
-
-    // Only applicable if the state == BROKEN.
-    IPCBlobCreationCancelCode broken_reason =
-        IPCBlobCreationCancelCode::UNKNOWN;
-
-    // data and data_builder are mutually exclusive.
-    std::unique_ptr<InternalBlobData> data;
-    std::unique_ptr<InternalBlobData::Builder> data_builder;
-
-    std::string content_type;
-    std::string content_disposition;
-
-    Entry() = delete;
-    Entry(int refcount, BlobState state);
-    ~Entry();
-
-    // Performs a test-and-set on the state of the given blob. If the state
-    // isn't as expected, we return false. Otherwise we set the new state and
-    // return true.
-    bool TestAndSetState(BlobState expected, BlobState set);
-  };
-
   BlobStorageRegistry();
   ~BlobStorageRegistry();
 
   // Creates the blob entry with a refcount of 1 and a state of PENDING. If
   // the blob is already in use, we return null.
-  Entry* CreateEntry(const std::string& uuid,
-                     const std::string& content_type,
-                     const std::string& content_disposition);
+  InternalBlobData* CreateEntry(const std::string& uuid,
+                                const std::string& content_type,
+                                const std::string& content_disposition);
 
   // Removes the blob entry with the given uuid. This does not unmap any
   // URLs that are pointing to this uuid. Returns if the entry existed.
   bool DeleteEntry(const std::string& uuid);
 
   bool HasEntry(const std::string& uuid) const;
 
   // Gets the blob entry for the given uuid. Returns nullptr if the entry
   // does not exist.
-  Entry* GetEntry(const std::string& uuid);
-  const Entry* GetEntry(const std::string& uuid) const;
+  InternalBlobData* GetEntry(const std::string& uuid);
+  const InternalBlobData* GetEntry(const std::string& uuid) const;
 
   // Creates a url mapping from blob uuid to the given url. Returns false if
   // the uuid isn't mapped to an entry or if there already is a map for the URL.
   bool CreateUrlMapping(const GURL& url, const std::string& uuid);
 
   // Removes the given URL mapping. Optionally populates a uuid string of the
   // removed entry uuid. Returns false if the url isn't mapped.
   bool DeleteURLMapping(const GURL& url, std::string* uuid);
 
   // Returns if the url is mapped to a blob uuid.
   bool IsURLMapped(const GURL& blob_url) const;
 
   // Returns the entry from the given url, and optionally populates the uuid for
   // that entry. Returns a nullptr if the mapping or entry doesn't exist.
-  Entry* GetEntryFromURL(const GURL& url, std::string* uuid);
+  InternalBlobData* GetEntryFromURL(const GURL& url, std::string* uuid);
 
   size_t blob_count() const { return blob_map_.size(); }
   size_t url_count() const { return url_to_uuid_.size(); }
 
  private:
   friend class ViewBlobInternalsJob;
-  using BlobMap = base::ScopedPtrHashMap<std::string, std::unique_ptr<Entry>>;
+  using BlobMap =
+      base::ScopedPtrHashMap<std::string, std::unique_ptr<InternalBlobData>>;
   using URLMap = std::map<GURL, std::string>;
 
   BlobMap blob_map_;
   URLMap url_to_uuid_;
 
   DISALLOW_COPY_AND_ASSIGN(BlobStorageRegistry);
 };
 
 }  // namespace storage
 #endif  // STORAGE_BROWSER_BLOB_BLOB_STORAGE_REGISTRY_H_