Add the method to check if offline archive is in internal dir

Bug: 758690
Change-Id: I8bb4283fc40a87fa7a87df2c7e513e2e16903290
Reviewed-on: https://chromium-review.googlesource.com/828049
Reviewed-by: Filip Gorski <fgorski@chromium.org>
Commit-Queue: Jian Li <jianli@chromium.org>
Cr-Commit-Position: refs/heads/master@{#524232}
void OfflinePageModelTaskified::ClearLegacyTemporaryPages() {
  auto task = base::MakeUnique<ClearLegacyTemporaryPagesTask>(
      store_.get(), policy_controller_.get(),
      archive_manager_->GetPersistentArchivesDir());
  task_queue_.AddTask(std::move(task));
}

void OfflinePageModelTaskified::ClearLegacyTemporaryPages() {
  auto task = base::MakeUnique<ClearLegacyTemporaryPagesTask>(
      store_.get(), policy_controller_.get(),
      archive_manager_->GetPersistentArchivesDir());
  task_queue_.AddTask(std::move(task));
}
