[Offline Prefetch] Backoff support for PrefetchBackgroundTask

chrome/common/pref_names.h

 // Copyright (c) 2012 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.
 
 // Constants for the names of various preferences, for easier changing.
 
 #ifndef CHROME_COMMON_PREF_NAMES_H_
 #define CHROME_COMMON_PREF_NAMES_H_
 
 #include <stddef.h>
 
 #include "build/build_config.h"
 #include "chrome/common/features.h"
+#include "components/offline_pages/features/features.h"
 #include "extensions/features/features.h"
 #include "media/media_features.h"
 #include "ppapi/features/features.h"
 #include "rlz/features/features.h"
 
 namespace prefs {
 
 // Profile prefs. Please add Local State prefs below instead.
 #if defined(OS_CHROMEOS) && BUILDFLAG(ENABLE_APP_LIST)
 extern const char kArcActiveDirectoryPlayUserId[];
@@ skipping 890 matching lines @@
 
 extern const char kSettingsResetPromptPromptWave[];
 extern const char kSettingsResetPromptLastTriggeredForDefaultSearch[];
 extern const char kSettingsResetPromptLastTriggeredForStartupUrls[];
 extern const char kSettingsResetPromptLastTriggeredForHomepage[];
 
 #if defined(OS_ANDROID)
 extern const char kClipboardLastModifiedTime[];
 #endif
 
+#if BUILDFLAG(ENABLE_OFFLINE_PAGES)
+extern const char kOfflinePrefetchBackoff[];
+#endif
+
 }  // namespace prefs
 
 #endif  // CHROME_COMMON_PREF_NAMES_H_