Add experiment flag for hiding articles on NTP

Bug: 803525
Change-Id: Ie97cf5306fbad1f095306651a4680e5718d3088c
Reviewed-on: https://chromium-review.googlesource.com/896393
Reviewed-by: Theresa <[email protected]>
Reviewed-by: Bernhard Bauer <[email protected]>
Commit-Queue: Becky Zhou <[email protected]>
Cr-Commit-Position: refs/heads/master@{#533685}
diff --git a/chrome/browser/flag_descriptions.h b/chrome/browser/flag_descriptions.h
index f460df5..622e8ce 100644
--- a/chrome/browser/flag_descriptions.h
+++ b/chrome/browser/flag_descriptions.h
@@ -1168,6 +1168,9 @@
 extern const char kEnableExpandedAutofillCreditCardPopupLayoutName[];
 extern const char kEnableExpandedAutofillCreditCardPopupLayoutDescription[];
 
+extern const char kEnableNtpArticleSuggestionsExpandableHeaderName[];
+extern const char kEnableNtpArticleSuggestionsExpandableHeaderDescription[];
+
 extern const char kEnableNtpAssetDownloadSuggestionsName[];
 extern const char kEnableNtpAssetDownloadSuggestionsDescription[];