Make GetDismissedSuggestionsForDebugging asynchronous

components/ntp_snippets/ntp_snippets_service.cc

 // Copyright 2015 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/ntp_snippets/ntp_snippets_service.h"
 
 #include <algorithm>
 #include <iterator>
 #include <utility>
 
@@ skipping 319 matching lines @@
 
   if (snippets_.empty())
     return;
 
   database_->DeleteSnippets(snippets_);
   snippets_.clear();
 
   NotifyNewSuggestions();
 }
 
-std::vector<ContentSuggestion>
-NTPSnippetsService::GetDismissedSuggestionsForDebugging(Category category) {
+void NTPSnippetsService::GetDismissedSuggestionsForDebugging(
+    Category category,
+    const DismissedSuggestionsCallback& callback) {
   DCHECK_EQ(category, provided_category_);
   std::vector<ContentSuggestion> result;
   for (const std::unique_ptr<NTPSnippet>& snippet : dismissed_snippets_) {
     if (!snippet->is_complete())
       continue;
     ContentSuggestion suggestion(
         MakeUniqueID(provided_category_, snippet->id()),
         snippet->best_source().url);
     suggestion.set_amp_url(snippet->best_source().amp_url);
     suggestion.set_title(base::UTF8ToUTF16(snippet->title()));
     suggestion.set_snippet_text(base::UTF8ToUTF16(snippet->snippet()));
     suggestion.set_publish_date(snippet->publish_date());
     suggestion.set_publisher_name(
         base::UTF8ToUTF16(snippet->best_source().publisher_name));
     suggestion.set_score(snippet->score());
     result.emplace_back(std::move(suggestion));
   }
-  return result;
+  callback.Run(std::move(result));
 }
 
 void NTPSnippetsService::ClearDismissedSuggestionsForDebugging(
     Category category) {
   DCHECK_EQ(category, provided_category_);
   if (!initialized())
     return;
 
   if (dismissed_snippets_.empty())
     return;
@@ skipping 469 matching lines @@
 void NTPSnippetsService::UpdateCategoryStatus(CategoryStatus status) {
   if (status == category_status_)
     return;
 
   category_status_ = status;
   observer()->OnCategoryStatusChanged(this, provided_category_,
                                       category_status_);
 }
 
 }  // namespace ntp_snippets