Remove safe_browsing=2 functionality, replace with =3 mode.

build/config/BUILD.gn

Index: build/config/BUILD.gn
diff --git a/build/config/BUILD.gn b/build/config/BUILD.gn
index 97d7d04c8f245b433d46e61c923c3922b6252d7d..64077ccf26eb8c96c87f03eef933b5afa9b966bb 100644
--- a/build/config/BUILD.gn
+++ b/build/config/BUILD.gn
@@ -259,14 +259,8 @@ config("feature_flags") {
     defines += [ "FULL_SAFE_BROWSING" ]
     defines += [ "SAFE_BROWSING_CSD" ]
     defines += [ "SAFE_BROWSING_DB_LOCAL" ]
-    defines += [ "SAFE_BROWSING_SERVICE" ]
   } else if (safe_browsing_mode == 2) {
-    defines += [ "MOBILE_SAFE_BROWSING" ]
-    defines += [ "SAFE_BROWSING_SERVICE" ]
-  } else if (safe_browsing_mode == 3) {
-    defines += [ "MOBILE_SAFE_BROWSING" ]
     defines += [ "SAFE_BROWSING_DB_REMOTE" ]
-    defines += [ "SAFE_BROWSING_SERVICE" ]
   }
   if (is_official_build) {
     defines += [ "OFFICIAL_BUILD" ]