chrome/blink: Add functionality for in-product help for media elements.

components/feature_engagement_tracker/public/feature_constants.cc

 /// Copyright 2017 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/feature_engagement_tracker/public/feature_constants.h"
 
 namespace feature_engagement_tracker {
 
 const base::Feature kIPHDemoMode{"IPH_DemoMode",
                                  base::FEATURE_DISABLED_BY_DEFAULT};
 
 const base::Feature kIPHDummyFeature{"IPH_Dummy",
                                      base::FEATURE_DISABLED_BY_DEFAULT};
 
 #if defined(OS_ANDROID)
 const base::Feature kIPHDataSaverPreviewFeature{
     "IPH_DataSaverPreview", base::FEATURE_DISABLED_BY_DEFAULT};
 const base::Feature kIPHDataSaverDetailFeature{
     "IPH_DataSaverDetail", base::FEATURE_DISABLED_BY_DEFAULT};
 const base::Feature kIPHDownloadPageFeature{"IPH_DownloadPage",
                                             base::FEATURE_DISABLED_BY_DEFAULT};
 const base::Feature kIPHDownloadHomeFeature{"IPH_DownloadHome",
                                             base::FEATURE_DISABLED_BY_DEFAULT};
+const base::Feature kIPHMediaDownloadFeature{"IPH_MediaDownload",
+                                             base::FEATURE_DISABLED_BY_DEFAULT};
 #endif  // OS_ANDROID
 
 }  // namespace feature_engagement_tracker