Allow category["suggestions"] to be absent.

components/ntp_snippets/ntp_snippets_fetcher.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/ntp_snippets_fetcher.h"
 
 #include <stdlib.h>
 
 #include "base/command_line.h"
 #include "base/files/file_path.h"
@@ skipping 519 matching lines @@
 
     case CHROME_CONTENT_SUGGESTIONS_API: {
       const base::ListValue* categories = nullptr;
       if (!top_dict->GetList("categories", &categories)) {
         return false;
       }
 
       for (const auto& v : *categories) {
         int category_id = -1;
         const base::DictionaryValue* category_value = nullptr;
-        const base::ListValue* suggestions = nullptr;
         if (!(v->GetAsDictionary(&category_value) &&
               category_value->GetInteger("id", &category_id) &&
-              (category_id > 0) &&
-              category_value->GetList("suggestions", &suggestions))) {
+              (category_id > 0))) {
           return false;
         }
         Category category = category_factory_->FromRemoteCategory(category_id);
+        const base::ListValue* suggestions = nullptr;
         NTPSnippet::PtrVector* articles = &(*snippets)[category];
+        if (!category_value->GetList("suggestions", &suggestions)) {
+          // Absence of a list of suggestions is treated as an empty list, which
+          // is permissible.
+          continue;
+        }
         if (!AddSnippetsFromListValue(
                 /* content_suggestions_api = */ true, *suggestions, articles)) {
           return false;
         }
       }
       return true;
     }
   }
   NOTREACHED();
   return false;
@@ skipping 35 matching lines @@
   }
   UMA_HISTOGRAM_ENUMERATION("NewTabPage.Snippets.FetchResult",
                             static_cast<int>(result),
                             static_cast<int>(FetchResult::RESULT_MAX));
 
   if (!snippets_available_callback_.is_null())
     snippets_available_callback_.Run(std::move(snippets));
 }
 
 }  // namespace ntp_snippets