Improve the page download:

components/offline_pages/offline_page_model_impl.cc

 // Copyright 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 "components/offline_pages/offline_page_model_impl.h"
 
 #include <algorithm>
 #include <limits>
 
 #include "base/bind.h"
@@ skipping 339 matching lines @@
   }
 
   // The web contents is not available if archiver is not created and passed.
   if (!archiver.get()) {
     InformSavePageDone(callback, SavePageResult::CONTENT_UNAVAILABLE, client_id,
                        kInvalidOfflineId);
     return;
   }
 
   // If we already have an offline id, use it.  If not, generate one.
-  if (proposed_offline_id == 0l)
+  if (proposed_offline_id == kInvalidOfflineId)
     proposed_offline_id = GenerateOfflineId();
 
   archiver->CreateArchive(
       archives_dir_, proposed_offline_id,
       base::Bind(&OfflinePageModelImpl::OnCreateArchiveDone,
                  weak_ptr_factory_.GetWeakPtr(), url, proposed_offline_id,
                  client_id, GetCurrentTime(), callback));
   pending_archivers_.push_back(std::move(archiver));
 }
 
@@ skipping 677 matching lines @@
   }
 
   base::ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE, task);
 }
 
 base::Time OfflinePageModelImpl::GetCurrentTime() const {
   return testing_clock_ ? testing_clock_->Now() : base::Time::Now();
 }
 
 }  // namespace offline_pages