Stop showing notifications if they're ignored

chrome/browser/ntp_snippets/ntp_snippets_features.h

Index: chrome/browser/ntp_snippets/ntp_snippets_features.h
diff --git a/chrome/browser/ntp_snippets/ntp_snippets_features.h b/chrome/browser/ntp_snippets/ntp_snippets_features.h
index 02a33f6a938194f8767b6ee8a3b361b8f877c2af..5e7817c4c248e6834ae647fec15237fb1c7e6c77 100644
--- a/chrome/browser/ntp_snippets/ntp_snippets_features.h
+++ b/chrome/browser/ntp_snippets/ntp_snippets_features.h
@@ -14,4 +14,9 @@ extern const base::Feature kContentSuggestionsNotificationsFeature;
 // "true": always send a notification when we receive ARTICLES suggestions
 extern const char kContentSuggestionsNotificationsAlwaysNotifyParam[];
 
+// An integer. The number of notifications that can be ignored. If the user
+// ignores this many notifications or more, we stop sending them.
+extern const char kContentSuggestionsNotificationsIgnoredLimitParam[];
+constexpr int kContentSuggestionsNotificationsIgnoredDefaultLimit = 3;
+
 #endif  // CHROME_BROWSER_NTP_SNIPPETS_NTP_SNIPPETS_FEATURES_H_