Offline Pages: Replace Observer::OfflinePageModelChanged with OfflinePageAdded.

components/offline_pages/offline_page_model_impl.cc

Index: components/offline_pages/offline_page_model_impl.cc
diff --git a/components/offline_pages/offline_page_model_impl.cc b/components/offline_pages/offline_page_model_impl.cc
index 9df2141e42d0a78c368c778df1e86e674993211d..a8e403b36bfdfa757396bed949cd259493f8c602 100644
--- a/components/offline_pages/offline_page_model_impl.cc
+++ b/components/offline_pages/offline_page_model_impl.cc
@@ -774,6 +774,7 @@ void OfflinePageModelImpl::OnAddOfflinePageDone(
     const OfflinePageItem& offline_page,
     ItemActionStatus status) {
   SavePageResult result;
+
   if (status == ItemActionStatus::SUCCESS) {
     offline_pages_[offline_page.offline_id] = offline_page;
     result = SavePageResult::SUCCESS;
@@ -796,8 +797,13 @@ void OfflinePageModelImpl::OnAddOfflinePageDone(
   }
 
   DeletePendingArchiver(archiver);
+
+  // We don't want to notify observers if the add failed.
+  if (result != SavePageResult::SUCCESS)
+    return;
+
   for (Observer& observer : observers_)
-    observer.OfflinePageModelChanged(this);
+    observer.OfflinePageAdded(this, offline_page);
 }
 
 void OfflinePageModelImpl::OnMarkPageAccesseDone(