Make GetBestPageForOnlineURL async

components/offline_pages/offline_page_model.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_MODEL_H_
 #define COMPONENTS_OFFLINE_PAGES_OFFLINE_PAGE_MODEL_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 147 matching lines @@
   // exists, depending on the implementation details of OfflinePageModel.
   // Use |GetPageByOfflineURL| instead.
   virtual const OfflinePageItem* MaybeGetPageByOfflineURL(
       const GURL& offline_url) const = 0;
 
   // Returns the offline pages that are stored under |online_url|.
   virtual void GetPagesByOnlineURL(
       const GURL& online_url,
       const MultipleOfflinePageItemCallback& callback) = 0;
 
-  // Returns via callback an offline page saved for |online_url|, if any. The
-  // best page is chosen based on creation date; a more recently created offline
-  // page will be preferred over an older one. This API function does not
-  // respect namespaces, as it is used to choose which page is rendered in a
-  // tab. Today all namespaces are treated equally for the purposes of this
-  // selection.
-  virtual void GetBestPageForOnlineURL(
-      const GURL& online_url,
-      const SingleOfflinePageItemCallback callback) = 0;
-
   // Returns an offline page saved for |online_url|. A nullptr is returned if
   // not found.  See |GetBestPageForOnlineURL| for selection criteria.
   virtual const OfflinePageItem* MaybeGetBestPageForOnlineURL(
       const GURL& online_url) const = 0;
 
   // Checks that all of the offline pages have corresponding offline copies,
   // and all archived files have offline pages pointing to them.
   // If a page is discovered to be missing an offline copy, its offline page
   // metadata will be expired. If an archive file is discovered missing its
   // offline page, it will be deleted.
@@ skipping 11 matching lines @@
   // TODO(dougarnett): Remove this and its uses.
   virtual bool is_loaded() const = 0;
 
   // Returns the logger. Ownership is retained by the model.
   virtual OfflineEventLogger* GetLogger() = 0;
 };
 
 }  // namespace offline_pages
 
 #endif  // COMPONENTS_OFFLINE_PAGES_OFFLINE_PAGE_MODEL_H_