[Downloads] Rework how hashes are calculated for download files.

content/public/browser/download_url_parameters.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_PUBLIC_BROWSER_DOWNLOAD_URL_PARAMETERS_H_
 #define CONTENT_PUBLIC_BROWSER_DOWNLOAD_URL_PARAMETERS_H_
 
 #include <stdint.h>
 #include <string>
 #include <utility>
@@ skipping 137 matching lines @@
 
   // Suggested filename for the download. The suggestion can be overridden by
   // either a Content-Disposition response header or a |file_path|.
   void set_suggested_name(const base::string16& suggested_name) {
     save_info_.suggested_name = suggested_name;
   }
 
   // If |offset| is non-zero, then a byte range request will be issued to fetch
   // the range of bytes starting at |offset| through to the end of thedownload.
   void set_offset(int64_t offset) { save_info_.offset = offset; }
-  void set_hash_state(const std::string& hash_state) {
-    save_info_.hash_state = hash_state;
+
+  // If |offset| is non-zero, then |hash_of_partial_file| contains the raw
+  // SHA-256 hash of the first |offset| bytes of the target file. Only
+  // meaningful if a partial file exists and is identified by either the
+  // |file_path()| or |file()|.
+  void set_hash_of_partial_file(const std::string& hash_of_partial_file) {
+    save_info_.hash_of_partial_file = hash_of_partial_file;
+  }
+
+  // If |offset| is non-zero, then |hash_state| indicates the SHA-256 hash state
+  // of the first |offset| bytes of the target file. In this case, the prefix
+  // hash will be ignored since the |hash_state| is assumed to be correct if
+  // provided.
+  void set_hash_state(scoped_ptr<crypto::SecureHash> hash_state) {
+    save_info_.hash_state = std::move(hash_state);
   }
 
   // If |prompt| is true, then the user will be prompted for a filename. Ignored
   // if |file_path| is non-empty.
   void set_prompt(bool prompt) { save_info_.prompt_for_save_location = prompt; }
   void set_file(base::File file) { save_info_.file = std::move(file); }
   void set_do_not_prompt_for_login(bool do_not_prompt) {
     do_not_prompt_for_login_ = do_not_prompt;
   }
 
@@ skipping 14 matching lines @@
   int render_frame_host_routing_id() const {
     return render_frame_host_routing_id_;
   }
   const RequestHeadersType& request_headers() const { return request_headers_; }
   ResourceContext* resource_context() const { return resource_context_; }
   const base::FilePath& file_path() const { return save_info_.file_path; }
   const base::string16& suggested_name() const {
     return save_info_.suggested_name;
   }
   int64_t offset() const { return save_info_.offset; }
-  const std::string& hash_state() const { return save_info_.hash_state; }
+  const std::string& hash_of_partial_file() const {
+    return save_info_.hash_of_partial_file;
+  }
   bool prompt() const { return save_info_.prompt_for_save_location; }
   const GURL& url() const { return url_; }
   bool do_not_prompt_for_login() const { return do_not_prompt_for_login_; }
 
-  // Note that this is state changing--the DownloadUrlParameters object
-  // will not have a file attached to it after this call.
-  base::File GetFile() { return std::move(save_info_.file); }
+  // STATE CHANGING: All save_info_ sub-objects will be in an indeterminate
+  // state following this call.
+  DownloadSaveInfo GetSaveInfo() { return std::move(save_info_); }
 
  private:
   OnStartedCallback callback_;
   bool content_initiated_;
   RequestHeadersType request_headers_;
   std::string last_modified_;
   std::string etag_;
   std::string method_;
   std::string post_body_;
   int64_t post_id_;
   bool prefer_cache_;
   Referrer referrer_;
   std::string referrer_encoding_;
   int render_process_host_id_;
   int render_view_host_routing_id_;
   int render_frame_host_routing_id_;
   ResourceContext* resource_context_;
   DownloadSaveInfo save_info_;
   GURL url_;
   bool do_not_prompt_for_login_;
 
   DISALLOW_COPY_AND_ASSIGN(DownloadUrlParameters);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_DOWNLOAD_URL_PARAMETERS_H_