Refactor the offline page storage to include client namespace and id.

components/offline_pages/offline_page_item.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 COMPONENTS_OFFLINE_PAGES_OFFLINE_PAGE_ITEM_H_
 #define COMPONENTS_OFFLINE_PAGES_OFFLINE_PAGE_ITEM_H_
 
 #include <stdint.h>
 
 #include <string>
 
 #include "base/files/file_path.h"
 #include "base/strings/string16.h"
 #include "base/time/time.h"
 #include "url/gurl.h"
 
 namespace offline_pages {
 
+class ClientId;
+
 // Metadata of the offline page.
 struct OfflinePageItem {
  public:
   // Note that this should match with Flags enum in offline_pages.proto.
   enum Flags {
     NO_FLAG = 0,
     MARKED_FOR_DELETION = 0x1,
   };
 
   OfflinePageItem();
   OfflinePageItem(const GURL& url,
-                  int64_t bookmark_id,
+                  int64_t offline_id,
+                  const ClientId& client_id,
                   const base::FilePath& file_path,
                   int64_t file_size);
   OfflinePageItem(const GURL& url,
-                  int64_t bookmark_id,
+                  int64_t offline_id,
+                  const ClientId& client_id,
                   const base::FilePath& file_path,
                   int64_t file_size,
                   const base::Time& creation_time);
   ~OfflinePageItem();
 
   // Gets a URL of the file under |file_path|.
   GURL GetOfflineURL() const;
 
   // Returns true if the page has been marked for deletion. This allows an undo
   // in a short time period. After that, the marked page will be deleted.
   bool IsMarkedForDeletion() const;
 
   // Sets/clears the mark for deletion.
   void MarkForDeletion();
   void ClearMarkForDeletion();
 
   // The URL of the page.
   GURL url;
-  // The Bookmark ID related to the offline page.
-  int64_t bookmark_id;
+  // The Offline (internal) ID related to the offline page.
+  int64_t offline_id;
+
+  // The Client ID (external) related to the offline page.
+  std::string client_id_namespace;
+  std::string client_id;
+
   // Version of the offline page item.
   int version;
   // The file path to the archive with a local copy of the page.
   base::FilePath file_path;
   // The size of the offline copy.
   int64_t file_size;
   // The time when the offline archive was created.
   base::Time creation_time;
   // The time when the offline archive was last accessed.
   base::Time last_access_time;
   // Number of times that the offline archive has been accessed.
   int access_count;
   // Flags about the state and behavior of the offline page.
   Flags flags;
 };
 
 }  // namespace offline_pages
 
 #endif  // COMPONENTS_OFFLINE_PAGES_OFFLINE_PAGE_ITEM_H_