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

components/offline_pages/offline_page_metadata_store_impl.h

Index: components/offline_pages/offline_page_metadata_store_impl.h
diff --git a/components/offline_pages/offline_page_metadata_store_impl.h b/components/offline_pages/offline_page_metadata_store_impl.h
index f9248c65e26bdc2b80644f5117ce2edf47034187..e9d822531fe64c7e52761a2835b9702b83d50505 100644
--- a/components/offline_pages/offline_page_metadata_store_impl.h
+++ b/components/offline_pages/offline_page_metadata_store_impl.h
@@ -42,7 +42,7 @@ class OfflinePageMetadataStoreImpl : public OfflinePageMetadataStore {
   void Load(const LoadCallback& callback) override;
   void AddOrUpdateOfflinePage(const OfflinePageItem& offline_page_record,
                               const UpdateCallback& callback) override;
-  void RemoveOfflinePages(const std::vector<int64_t>& bookmark_ids,
+  void RemoveOfflinePages(const std::vector<int64_t>& offline_ids,
                           const UpdateCallback& callback) override;
   void Reset(const ResetCallback& callback) override;
 
@@ -67,6 +67,14 @@ class OfflinePageMetadataStoreImpl : public OfflinePageMetadataStore {
 
   void ResetDone(const ResetCallback& callback, bool success);
 
+  // Called when a database has to be migrated from old bookmark ids
+  // to new offline ids.
+  // TODO: Remove this eventually.
+  void DatabaseUpdateDone(const OfflinePageMetadataStore::LoadCallback& cb,
+                          LoadStatus status,
+                          const std::vector<OfflinePageItem>& result,
+                          bool success);
+
   scoped_refptr<base::SequencedTaskRunner> background_task_runner_;
   base::FilePath database_dir_;
   scoped_ptr<leveldb_proto::ProtoDatabase<OfflinePageEntry>> database_;