sync: add WIFI_CREDENTIALS protobuf, ModelType, and preference

sync/protocol/proto_enum_conversions.cc

Index: sync/protocol/proto_enum_conversions.cc
diff --git a/sync/protocol/proto_enum_conversions.cc b/sync/protocol/proto_enum_conversions.cc
index d8c1f0b594261e4dd0584a8d357ec3081eeef476..7ee112c6c57fd658acd9c6ee52c1395c55ffb580 100644
--- a/sync/protocol/proto_enum_conversions.cc
+++ b/sync/protocol/proto_enum_conversions.cc
@@ -80,6 +80,19 @@ const char* GetPageTransitionRedirectTypeString(
   return "";
 }
 
+const char* GetWifiCredentialSecurityClassString(
+    sync_pb::WifiCredentialSpecifics::SecurityClass security_class) {
+  ASSERT_ENUM_BOUNDS(sync_pb::WifiCredentialSpecifics, SecurityClass,
+                     SECURITY_CLASS_INVALID, SECURITY_CLASS_PSK);
+  switch (security_class) {
+    ENUM_CASE(sync_pb::WifiCredentialSpecifics, SECURITY_CLASS_INVALID);
+    ENUM_CASE(sync_pb::WifiCredentialSpecifics, SECURITY_CLASS_NONE);
+    ENUM_CASE(sync_pb::WifiCredentialSpecifics, SECURITY_CLASS_WEP);
+    ENUM_CASE(sync_pb::WifiCredentialSpecifics, SECURITY_CLASS_PSK);
+  }
+  NOTREACHED();
+  return "";
+}
 const char* GetUpdatesSourceString(
     sync_pb::GetUpdatesCallerInfo::GetUpdatesSource updates_source) {
   ASSERT_ENUM_BOUNDS(sync_pb::GetUpdatesCallerInfo, GetUpdatesSource,