Store original request URL in offline page metadata table

components/offline_pages/offline_page_model.cc

Index: components/offline_pages/offline_page_model.cc
diff --git a/components/offline_pages/offline_page_model.cc b/components/offline_pages/offline_page_model.cc
index cd0a93705f20b8ed1807c2f807e2a1641a37f4f7..b24bb5374d9a250348dbc19f390181a35c2b262d 100644
--- a/components/offline_pages/offline_page_model.cc
+++ b/components/offline_pages/offline_page_model.cc
@@ -8,6 +8,10 @@
 
 namespace offline_pages {
 
+OfflinePageModel::SavePageInfo::SavePageInfo()
+    : proposed_offline_id(OfflinePageModel::kInvalidOfflineId) {
+}
+
 // static
 bool OfflinePageModel::CanSaveURL(const GURL& url) {
   return url.is_valid() && url.SchemeIsHTTPOrHTTPS();