[Offline Pages] Fix cases where returning NOT_FOUND when deleting.

chrome/browser/android/offline_pages/recent_tab_helper.cc

 // Copyright (c) 2016 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.
 
 #include "chrome/browser/android/offline_pages/recent_tab_helper.h"
 
 #include <queue>
 #include <vector>
 
 #include "base/bind.h"
@@ skipping 134 matching lines @@
     pages_queue.pop();
   }
 
   page_model_->DeletePagesByOfflineId(
       pages_to_purge, base::Bind(&RecentTabHelper::ContinueSnapshotAfterPurge,
                                  weak_ptr_factory_.GetWeakPtr()));
 }
 
 void RecentTabHelper::ContinueSnapshotAfterPurge(
     OfflinePageModel::DeletePageResult result) {
-  // NOT_FOUND is because it's what we get when passing empty vector of ids.
-  // TODO(dimich): remove NOT_FOUND when bug 608057 is fixed.
-  if (result != OfflinePageModel::DeletePageResult::SUCCESS &&
-      result != OfflinePageModel::DeletePageResult::NOT_FOUND) {
+  if (result != OfflinePageModel::DeletePageResult::SUCCESS) {
     // If previous pages can't be deleted, don't add new ones.
     ReportSnapshotCompleted();
     return;
   }
 
   if (!IsSamePage()) {
     ReportSnapshotCompleted();
     return;
   }
 
@@ skipping 33 matching lines @@
     std::unique_ptr<TestArchiveFactory> test_archive_factory) {
   test_archive_factory_ = std::move(test_archive_factory);
 }
 
 void RecentTabHelper::SetTaskRunnerForTest(
     const scoped_refptr<base::SingleThreadTaskRunner>& task_runner) {
   snapshot_controller_.reset(new SnapshotController(task_runner, this));
 }
 
 }  // namespace offline_pages