[NTP Snippets] Add a flag to not restrict snippets by ML suggestions

components/ntp_snippets/switches.cc

Index: components/ntp_snippets/switches.cc
diff --git a/components/ntp_snippets/switches.cc b/components/ntp_snippets/switches.cc
index 48c6ddaf5dadcf9a7a390644ce312719bad35498..4fdbf2bb9fa60428f84aa431400dd9e05777b3c5 100644
--- a/components/ntp_snippets/switches.cc
+++ b/components/ntp_snippets/switches.cc
@@ -14,5 +14,9 @@ const char kFetchingIntervalWifiSeconds[] =
 const char kFetchingIntervalFallbackSeconds[] =
     "ntp-snippets-fetching-interval-fallback";
 
+// If this flag is set, the snippets won't be restricted to the user's NTP
+// suggestions.
+const char kDontRestrict[] = "ntp-snippets-dont-restrict";
+
 }  // namespace switches
 }  // namespace ntp_snippets