Failed offline snapshots won't erase a successful one from the same page load.

chrome/browser/android/offline_pages/recent_tab_helper.h

Index: chrome/browser/android/offline_pages/recent_tab_helper.h
diff --git a/chrome/browser/android/offline_pages/recent_tab_helper.h b/chrome/browser/android/offline_pages/recent_tab_helper.h
index 7a2199986945f4cd4328664412f7f5e8b1910b3b..664c2c76398d65702f47d00273b36d0ab9d16b51 100644
--- a/chrome/browser/android/offline_pages/recent_tab_helper.h
+++ b/chrome/browser/android/offline_pages/recent_tab_helper.h
@@ -98,6 +98,7 @@ class RecentTabHelper
   void ContinueSnapshotAfterPurge(OfflinePageModel::DeletePageResult result);
   void SavePageCallback(OfflinePageModel::SavePageResult result,
                         int64_t offline_id);
+  void PreviousSaveWasPurged(OfflinePageModel::DeletePageResult result);
   void ReportSnapshotCompleted();
   void ReportDownloadStatusToRequestCoordinator();
   bool IsSamePage() const;
@@ -119,6 +120,10 @@ class RecentTabHelper
   // current page.
   std::unique_ptr<DownloadPageInfo> download_info_;
 
+  // Stores the request/offline ID of successful snapshots that happened during
+  // a single ongoing page load.
+  int64_t previous_request_id_for_load_;
+
   // If empty, the tab does not have AndroidId and can not capture pages.
   std::string tab_id_;