[NTP] Propagate OfflineId from C++ for Downloads.

chrome/browser/ntp_snippets/download_suggestions_provider.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 "chrome/browser/ntp_snippets/download_suggestions_provider.h"
 
 #include <algorithm>
 #include <utility>
 
 #include "base/bind.h"
@@ skipping 470 matching lines @@
     // TODO(vitaliii): Remove this fallback once the OfflinePageModel provides
     // titles for all (relevant) OfflinePageItems.
     suggestion.set_title(base::UTF8ToUTF16(offline_page.url.spec()));
   } else {
     suggestion.set_title(offline_page.title);
   }
   suggestion.set_publish_date(offline_page.creation_time);
   suggestion.set_publisher_name(base::UTF8ToUTF16(offline_page.url.host()));
   auto extra = base::MakeUnique<ntp_snippets::DownloadSuggestionExtra>();
   extra->is_download_asset = false;
+  extra->offline_page_id = base::Int64ToString(offline_page.offline_id);

[Marc Treib, 2016/11/16 15:22:58]

Er, any reason why we pass this as a string? Seems like the Java side just
converts it back to an int?

[vitaliii, 2016/11/16 15:45:08]

As we discussed it is not clear how to match int64 on Java side, so TODO for
now.

[Marc Treib, 2016/11/16 15:55:56]

There's a jlong analogous to jint, I'm pretty sure that does the right thing :)
Anyway, this is fine in a followup.

[vitaliii, 2016/11/16 15:59:23]

Acknowledged.

   suggestion.set_download_suggestion_extra(std::move(extra));
   return suggestion;
 }
 
 ContentSuggestion DownloadSuggestionsProvider::ConvertDownloadItem(
     const DownloadItem& download_item) const {
   ContentSuggestion suggestion(
       ContentSuggestion::ID(provided_category_, GetAssetDownloadPerCategoryID(
                                                     download_item.GetId())),
       download_item.GetOriginalUrl());
@@ skipping 213 matching lines @@
 
 void DownloadSuggestionsProvider::UnregisterDownloadItemObservers() {
   DCHECK_NE(download_manager_, nullptr);
 
   std::vector<DownloadItem*> all_downloads;
   download_manager_->GetAllDownloads(&all_downloads);
 
   for (DownloadItem* item : all_downloads)
     item->RemoveObserver(this);
 }