Display status message for "Add snippets" on chrome://snippets-internals

components/ntp_snippets/ntp_snippets_fetcher.h

 // 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.
 
 #ifndef COMPONENTS_NTP_SNIPPETS_NTP_SNIPPETS_FETCHER_H_
 #define COMPONENTS_NTP_SNIPPETS_NTP_SNIPPETS_FETCHER_H_
 
 #include <set>
 #include <string>
 
 #include "base/callback.h"
 #include "base/callback_list.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "base/sequenced_task_runner.h"
 #include "net/url_request/url_fetcher_delegate.h"
 #include "net/url_request/url_request_context_getter.h"
 
 namespace ntp_snippets {
 
 // Fetches snippet data for the NTP from the server
 class NTPSnippetsFetcher : public net::URLFetcherDelegate {
  public:
-  using SnippetsAvailableCallback = base::Callback<void(const std::string&)>;
+  // If problems occur (explained in |status_message|), |snippets_json| is
+  // empty; otherwise, |status_message| is empty.
+  using SnippetsAvailableCallback =
+      base::Callback<void(const std::string& snippets_json,
+                          const std::string& status_message)>;
   using SnippetsAvailableCallbackList =
-      base::CallbackList<void(const std::string&)>;
+      base::CallbackList<void(const std::string&, const std::string&)>;
 
   NTPSnippetsFetcher(
       scoped_refptr<base::SequencedTaskRunner> file_task_runner,
       scoped_refptr<net::URLRequestContextGetter> url_request_context_getter,
       bool is_stable_channel);
   ~NTPSnippetsFetcher() override;
 
   // Adds a callback that is called when a new set of snippets are downloaded.
   scoped_ptr<SnippetsAvailableCallbackList::Subscription> AddCallback(
       const SnippetsAvailableCallback& callback) WARN_UNUSED_RESULT;
@@ skipping 20 matching lines @@
   SnippetsAvailableCallbackList callback_list_;
 
   // Flag for picking the right (stable/non-stable) API key for Chrome Reader
   bool is_stable_channel_;
 
   DISALLOW_COPY_AND_ASSIGN(NTPSnippetsFetcher);
 };
 }  // namespace ntp_snippets
 
 #endif  // COMPONENTS_NTP_SNIPPETS_NTP_SNIPPETS_FETCHER_H_