Improve DCHECK log to help in debugging its triggering, yet again

Now also logging the offline_id.

TBR=johnchen@chromium.org

Bug: 852616
Change-Id: Ic28d9a59da5ff81b0da7b640044799fad4538b71
Reviewed-on: https://chromium-review.googlesource.com/1105566Reviewed-by: Carlos Knippschild <carlosk@chromium.org>
Commit-Queue: Carlos Knippschild <carlosk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#568333}

chrome/browser/offline_pages/recent_tab_helper.cc

@@ -468,9 +468,9 @@ void RecentTabHelper::SavePageCallback(SnapshotProgressInfo* snapshot_info,
   DCHECK((snapshot_info->IsForLastN() &&
           snapshot_info->request_id == OfflinePageModel::kInvalidOfflineId) ||
          snapshot_info->request_id == offline_id)
-      << "SnapshotProgressInfo: client_id=" << snapshot_info->client_id
+      << "SnapshotProgressInfo(client_id=" << snapshot_info->client_id
       << ", request_id=" << snapshot_info->request_id
-      << ", origin=" << snapshot_info->origin;
+      << ", origin=" << snapshot_info->origin << "), offline_id=" << offline_id;
   // Store the assigned offline_id (for downloads case it will already contain
   // the same value).
   snapshot_info->request_id = offline_id;