Add finch control of user population in low reputation requests

components/safe_browsing/csd.proto

Index: components/safe_browsing/csd.proto
diff --git a/components/safe_browsing/csd.proto b/components/safe_browsing/csd.proto
index a69cd10bba7179ee99e34a5f417b79702a255726..a5fa8fe6d9b7530f14aaeaed47b90612f0176279 100644
--- a/components/safe_browsing/csd.proto
+++ b/components/safe_browsing/csd.proto
@@ -34,6 +34,14 @@ message ChromeUserPopulation {
     EXTENDED_REPORTING = 2;
   }
   optional UserPopulation user_population = 1;
+
+  // If user enabled history sync.
+  optional bool is_history_sync_enabled = 2;
+
+  // The finch active group this user belongs to (if any). Active group is
+  // defined by finch trial name and group name. Trial name and group name are
+  // concatenated with separator "|", e.g. "PingOnlyTrial|DefaultGroup".
+  repeated string finch_active_groups = 4;
 }
 
 message ClientPhishingRequest {
@@ -214,6 +222,9 @@ message LoginReputationClientRequest {
 
   // The number of verdicts stored on the client.
   optional int32 stored_verdict_cnt = 5;
+
+  // Chrome user population.
+  optional ChromeUserPopulation population = 6;
 }
 
 // The message is used for client response for login reputation requests.