Initial work to move downloads to ContentIds

components/offline_items_collection/core/offline_item.h

 // Copyright 2017 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_ITEMS_COLLECTION_CORE_OFFLINE_ITEM_H_
 #define COMPONENTS_OFFLINE_ITEMS_COLLECTION_CORE_OFFLINE_ITEM_H_
 
 #include <string>
 
 #include "base/time/time.h"
 #include "components/offline_items_collection/core/offline_item_filter.h"
 #include "components/offline_items_collection/core/offline_item_state.h"
 #include "url/gurl.h"
 
 namespace offline_items_collection {
 
 // An id that uniquely represents a piece of offline content.
 struct ContentId {
   // The namespace for the offline content.  This will be used to associate this
-  // id with a particular OfflineContentProvider.
+  // id with a particular OfflineContentProvider.  A name_space can include
+  // any characters except ','.  This is due to a serialization format
+  // limitation.
+  // TODO(dtrainor): Remove the 'no ,' limitation.
   std::string name_space;
 
   // The id of the offline item.
   std::string id;
 
   ContentId();
   ContentId(const ContentId& other);
   ContentId(const std::string& name_space, const std::string& id);
 
   ~ContentId();
@@ skipping 84 matching lines @@
 
   // The estimated time remaining for the download in milliseconds.  -1
   // represents an unknown time remaining.  This field is not used if |state| is
   // COMPLETE.
   int64_t time_remaining_ms;
 };
 
 }  // namespace offline_items_collection
 
 #endif  // COMPONENTS_OFFLINE_ITEMS_COLLECTION_OFFLINE_ITEM_H_