[BlobAsync] Disk support for blob storage

content/browser/blob_storage/chrome_blob_storage_context.h

 // Copyright (c) 2012 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_FILEAPI_CHROME_BLOB_STORAGE_CONTEXT_H_
 #define CONTENT_BROWSER_FILEAPI_CHROME_BLOB_STORAGE_CONTEXT_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <memory>
 
+#include "base/files/file_path.h"
 #include "base/memory/ref_counted.h"
 #include "base/sequenced_task_runner_helpers.h"
 #include "content/common/content_export.h"
 
 namespace base {
 class FilePath;
 class Time;
 }
 
 namespace storage {
 class BlobStorageContext;
 }
 
 namespace content {
 class BlobHandle;
 class BrowserContext;
 struct ChromeBlobStorageContextDeleter;
 
 // A context class that keeps track of BlobStorageController used by the chrome.
 // There is an instance associated with each BrowserContext. There could be
 // multiple URLRequestContexts in the same browser context that refers to the
 // same instance.
 //
 // All methods, except the ctor, are expected to be called on
 // the IO thread (unless specifically called out in doc comments).
 class CONTENT_EXPORT ChromeBlobStorageContext
     : public base::RefCountedThreadSafe<ChromeBlobStorageContext,
                                         ChromeBlobStorageContextDeleter> {
  public:
-  ChromeBlobStorageContext();
+  explicit ChromeBlobStorageContext();
 
   static ChromeBlobStorageContext* GetFor(
       BrowserContext* browser_context);
 
   void InitializeOnIOThread();
 
   storage::BlobStorageContext* context() const { return context_.get(); }
 
   // Returns a NULL scoped_ptr on failure.
   std::unique_ptr<BlobHandle> CreateMemoryBackedBlob(const char* data,
@@ skipping 10 matching lines @@
   virtual ~ChromeBlobStorageContext();
 
  private:
   friend class base::DeleteHelper<ChromeBlobStorageContext>;
   friend class base::RefCountedThreadSafe<ChromeBlobStorageContext,
                                           ChromeBlobStorageContextDeleter>;
   friend struct ChromeBlobStorageContextDeleter;
 
   void DeleteOnCorrectThread() const;
 
+  // Called after successfully creating our blob directory. This enables disk
+  // usage on |context_|.
+  void OnBlobDirectoryCreated(const base::FilePath& blob_storage_directory);
+
+  base::FilePath blob_storage_dir_;
   std::unique_ptr<storage::BlobStorageContext> context_;
 };
 
 struct ChromeBlobStorageContextDeleter {
   static void Destruct(const ChromeBlobStorageContext* context) {
     context->DeleteOnCorrectThread();
   }
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_FILEAPI_CHROME_BLOB_STORAGE_CONTEXT_H_