Revert of [Blob] BlobReader class & tests, and removal of all redundant reading.

storage/browser/blob/blob_url_request_job.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 STORAGE_BROWSER_BLOB_BLOB_URL_REQUEST_JOB_H_
 #define STORAGE_BROWSER_BLOB_BLOB_URL_REQUEST_JOB_H_
 
 #include <map>
 #include <vector>
 
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "net/http/http_byte_range.h"
 #include "net/http/http_status_code.h"
 #include "net/url_request/url_request_job.h"
+#include "storage/browser/blob/blob_data_snapshot.h"
 #include "storage/browser/storage_browser_export.h"
 
 namespace base {
 class SingleThreadTaskRunner;
 }
 
 namespace net {
 class DrainableIOBuffer;
 class IOBuffer;
 }
 
 namespace storage {
 
-class BlobDataHandle;
-class BlobReader;
 class FileStreamReader;
 class FileSystemContext;
 
 // A request job that handles reading blob URLs.
 class STORAGE_EXPORT BlobURLRequestJob
     : public net::URLRequestJob {
  public:
   BlobURLRequestJob(net::URLRequest* request,
                     net::NetworkDelegate* network_delegate,
-                    BlobDataHandle* blob_handle,
+                    scoped_ptr<BlobDataSnapshot> blob_data,
                     storage::FileSystemContext* file_system_context,
                     base::SingleThreadTaskRunner* resolving_thread_task_runner);
 
   // net::URLRequestJob methods.
   void Start() override;
   void Kill() override;
   bool ReadRawData(net::IOBuffer* buf, int buf_size, int* bytes_read) override;
   bool GetMimeType(std::string* mime_type) const override;
   void GetResponseInfo(net::HttpResponseInfo* info) override;
   int GetResponseCode() const override;
   void SetExtraRequestHeaders(const net::HttpRequestHeaders& headers) override;
 
  protected:
   ~BlobURLRequestJob() override;
 
  private:
   typedef std::map<size_t, FileStreamReader*> IndexToReaderMap;
 
   // For preparing for read: get the size, apply the range and perform seek.
   void DidStart();
-  void DidCalculateSize(int result);
-  void DidReadRawData(int result);
+  bool AddItemLength(size_t index, int64 item_length);
+  bool CountSize();
+  void DidCountSize(int error);
+  void DidGetFileItemLength(size_t index, int64 result);
+  void Seek(int64 offset);
 
+  // For reading the blob.
+  bool ReadLoop(int* bytes_read);
+  bool ReadItem();
+  void AdvanceItem();
+  void AdvanceBytesRead(int result);
+  bool ReadBytesItem(const BlobDataItem& item, int bytes_to_read);
+
+  bool ReadFileItem(FileStreamReader* reader, int bytes_to_read);
+  void DidReadFile(int chunk_number, int result);
+  void DeleteCurrentFileReader();
+
+  bool ReadDiskCacheEntryItem(const BlobDataItem& item, int bytes_to_read);
+  void DidReadDiskCacheEntry(int result);
+
+  int ComputeBytesToRead() const;
+  int BytesReadCompleted();
+
+  // These methods convert the result of blob data reading into response headers
+  // and pass it to URLRequestJob's NotifyDone() or NotifyHeadersComplete().
+  void NotifySuccess();
   void NotifyFailure(int);
   void HeadersCompleted(net::HttpStatusCode status_code);
 
+  // Returns a FileStreamReader for a blob item at |index|.
+  // If the item at |index| is not of file this returns NULL.
+  FileStreamReader* GetFileStreamReader(size_t index);
+
+  // Creates a FileStreamReader for the item at |index| with additional_offset.
+  // If failed, then returns false.
+  bool CreateFileStreamReader(size_t index, int64 additional_offset);
+
+  scoped_ptr<BlobDataSnapshot> blob_data_;
+
+  // Variables for controlling read from |blob_data_|.
+  scoped_refptr<storage::FileSystemContext> file_system_context_;
+  scoped_refptr<base::SingleThreadTaskRunner> file_task_runner_;
+  std::vector<int64> item_length_list_;
+  int64 total_size_;
+  int64 remaining_bytes_;
+  int pending_get_file_info_count_;
+  IndexToReaderMap index_to_reader_;
+  size_t current_item_index_;
+  int64 current_item_offset_;
+
+  // Holds the buffer for read data with the IOBuffer interface.
+  scoped_refptr<net::DrainableIOBuffer> read_buf_;
+
   // Is set when NotifyFailure() is called and reset when DidStart is called.
   bool error_;
 
   bool byte_range_set_;
   net::HttpByteRange byte_range_;
 
-  scoped_ptr<BlobDataHandle> blob_handle_;
-  scoped_ptr<BlobReader> blob_reader_;
+  // Used to create unique id's for tracing.
+  int current_file_chunk_number_;
+
   scoped_ptr<net::HttpResponseInfo> response_info_;
 
   base::WeakPtrFactory<BlobURLRequestJob> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(BlobURLRequestJob);
 };
 
 }  // namespace storage
 
 #endif  // STORAGE_BROWSER_BLOB_BLOB_URL_REQUEST_JOB_H_