Supplimentary identifier for passwords specific

components/sync/protocol/password_specifics.proto

Index: components/sync/protocol/password_specifics.proto
diff --git a/components/sync/protocol/password_specifics.proto b/components/sync/protocol/password_specifics.proto
index ad8c9f7146c91c8a1fb37a5b6bc928951b0821b1..5c52246cfc5e4870c2ce2cff56963fa9545dc176 100644
--- a/components/sync/protocol/password_specifics.proto
+++ b/components/sync/protocol/password_specifics.proto
@@ -110,6 +110,11 @@ message PasswordSpecificsData {
   optional string federation_url = 17;
 }
 
+// Contains the password specifics metadata which simplifies its lookup.
+message PasswordSpecificsMetadata {
+  optional string url = 1;
+};
+
 // Properties of password sync objects.
 message PasswordSpecifics {
   // The actual password data. Contains an encrypted PasswordSpecificsData
@@ -118,4 +123,8 @@ message PasswordSpecifics {
   // An unsynced field for use internally on the client. This field should
   // never be set in any network-based communications.
   optional PasswordSpecificsData client_only_encrypted_data = 2;
+  // Password related metadata, which is sent to the server side. The field
+  // should never be set for full encryption users. If encryption is enabled,
+  // this field must be cleared.
+  optional PasswordSpecificsMetadata unencrypted_metadata = 3;
 }