Make GetDismissedSuggestionsForDebugging asynchronous

components/ntp_snippets/bookmarks/bookmark_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 "components/ntp_snippets/bookmarks/bookmark_suggestions_provider.h"
 
 #include <utility>
 #include <vector>
 
 #include "base/bind.h"
@@ skipping 109 matching lines @@
   base::ThreadTaskRunnerHandle::Get()->PostTask(
       FROM_HERE, base::Bind(callback, suggestion_id, gfx::Image()));
 }
 
 void BookmarkSuggestionsProvider::ClearCachedSuggestionsForDebugging(
     Category category) {
   DCHECK_EQ(category, provided_category_);
   // Ignored.
 }
 
-std::vector<ContentSuggestion>
-BookmarkSuggestionsProvider::GetDismissedSuggestionsForDebugging(
-    Category category) {
+void BookmarkSuggestionsProvider::GetDismissedSuggestionsForDebugging(
+    Category category,
+    const DismissedSuggestionsCallback& callback) {
   DCHECK_EQ(category, provided_category_);
   std::vector<const BookmarkNode*> bookmarks =
       GetDismissedBookmarksForDebugging(bookmark_model_);
 
   std::vector<ContentSuggestion> suggestions;
   for (const BookmarkNode* bookmark : bookmarks)
     suggestions.emplace_back(ConvertBookmark(bookmark));
-  return suggestions;
+  callback.Run(std::move(suggestions));
 }
 
 void BookmarkSuggestionsProvider::ClearDismissedSuggestionsForDebugging(
     Category category) {
   DCHECK_EQ(category, provided_category_);
   if (!bookmark_model_->loaded())
     return;
   MarkAllBookmarksUndismissed(bookmark_model_);
 }
 
@@ skipping 87 matching lines @@
 
 void BookmarkSuggestionsProvider::NotifyStatusChanged(
     CategoryStatus new_status) {
   if (category_status_ == new_status)
     return;
   category_status_ = new_status;
   observer()->OnCategoryStatusChanged(this, provided_category_, new_status);
 }
 
 }  // namespace ntp_snippets