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

components/feature_engagement/public/feature_constants.cc

Index: components/feature_engagement/public/feature_constants.cc
diff --git a/components/feature_engagement/public/feature_constants.cc b/components/feature_engagement/public/feature_constants.cc
index 45680e1c2e6aba7799ccc4eae7516af76b9909bd..eb66d1f38a3006145cf2b8d7307cdd678cb98cb3 100644
--- a/components/feature_engagement/public/feature_constants.cc
+++ b/components/feature_engagement/public/feature_constants.cc
@@ -25,6 +25,8 @@ const base::Feature kIPHDownloadPageScreenshotFeature{
     "IPH_DownloadPageScreenshot", base::FEATURE_DISABLED_BY_DEFAULT};
 const base::Feature kIPHChromeHomeExpandFeature{
     "IPH_ChromeHomeExpand", base::FEATURE_DISABLED_BY_DEFAULT};
+const base::Feature kIPHMediaDownloadFeature{"IPH_MediaDownload",
+                                             base::FEATURE_DISABLED_BY_DEFAULT};
 #endif  // defined(OS_ANDROID)
 
 #if defined(OS_WIN) || defined(OS_LINUX)