[sync] Add store version to model type store backend

components/sync/PRESUBMIT.py

 # Copyright (c) 2016 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Presubmit script for sync
 This checks that ModelTypeInfo entries in model_type.cc follow conventions.
 See CheckModelTypeInfoMap or model_type.cc for more detail on the rules.
 """
 
 import os
 
 # Some definitions don't follow all the conventions we want to enforce.
 # It's either difficult or impossible to fix this, so we ignore the problem(s).
 GRANDFATHERED_MODEL_TYPES = [
   'UNSPECIFIED',  # Doesn't have a root tag or notification type.
   'TOP_LEVEL_FOLDER',  # Doesn't have a root tag or notification type.
   'AUTOFILL_WALLET_DATA',  # Root tag and model type string lack DATA suffix.
   'APP_SETTINGS',  # Model type string has inconsistent capitalization.
   'EXTENSION_SETTINGS',  # Model type string has inconsistent capitalization.
   'SUPERVISED_USER_SETTINGS',  # Root tag and model type string replace
                  # 'Supervised' with 'Managed'
   'SUPERVISED_USERS',  # See previous.
   'SUPERVISED_USER_WHITELISTS',  # See previous.
   'SUPERVISED_USER_SHARED_SETTINGS',  # See previous.
   'PROXY_TABS',  # Doesn't have a root tag or notification type.
   'NIGORI']  # Model type string is 'encryption keys'.
 
+# Root tags are used as prefixes when creating storage keys, so certain strings
+# are blacklisted in order to prevent prefix collision.
+BLACKLISTED_ROOT_TAGS = [
+  '_mts_schema_descriptor'
+]
+
 # Number of distinct fields in a map entry; used to create
 # sets that check for uniqueness.
 MAP_ENTRY_FIELD_COUNT = 6
 
 # String that precedes the ModelType when referencing the
 # proto field number enum e.g.
 # sync_pb::EntitySpecifics::kManagedUserFieldNumber.
 # Used to map from enum references to the ModelType.
 FIELD_NUMBER_PREFIX = 'sync_pb::EntitySpecifics::k'
 
@@ skipping 68 matching lines @@
   proto_field_definitions = ParseSyncProtoFieldIdentifiers(
     input_api, os.path.abspath(PROTO_FILE_PATH))
   accumulated_problems.extend(
     CheckNoDuplicatedFieldValues(output_api, map_entries))
 
   for map_entry in map_entries:
     entry_problems = []
     entry_problems.extend(
       CheckNotificationTypeMatchesProtoMessageName(
         output_api, map_entry, proto_field_definitions))
+    entry_problems.extend(CheckRootTagNotInBlackList(output_api, map_entry))
 
     if map_entry.model_type not in GRANDFATHERED_MODEL_TYPES:
       entry_problems.extend(
         CheckModelTypeStringMatchesModelType(output_api, map_entry))
       entry_problems.extend(
         CheckRootTagMatchesModelType(output_api, map_entry))
 
     if len(entry_problems) > 0:
       accumulated_problems.extend(entry_problems)
 
@@ skipping 210 matching lines @@
   expected_root_tag = map_entry.model_type.lower()
   if (StripTrailingS(expected_root_tag) !=
     StripTrailingS(map_entry.root_tag)):
     return [
       FormatPresubmitError(
         output_api,'root tag "%s" does not match model type. It should'
         'be "%s"' % (map_entry.root_tag, expected_root_tag),
         map_entry.affected_lines)]
   return []
 
+def CheckRootTagNotInBlackList(output_api, map_entry):
+  """ Checks that map_entry's root isn't a blacklisted string.
+  Args:
+    output_api: presubmit_support OutputAPI instance
+    map_entry: ModelTypeEnumEntry object to check
+  Returns:
+    A list of PresubmitError objects for each violation
+  """
+  if map_entry.root_tag in BLACKLISTED_ROOT_TAGS:
+    return [FormatPresubmitError(
+        output_api,'root tag "%s" is a blacklisted root tag'
+        % (map_entry.root_tag), map_entry.affected_lines)]
+  return []
+
 
 def FieldNumberToPrototypeString(field_number):
   """Converts a field number enum reference to an EntitySpecifics string.
   Converts a reference to the field number enum to the corresponding
   proto data type string.
   Args:
     field_number: string representation of a field number enum reference
   Returns:
     A string that is the corresponding proto field data type. e.g.
     FieldNumberToPrototypeString('EntitySpecifics::kAppFieldNumber')
     => 'AppSpecifics'
   """
   return field_number.replace(FIELD_NUMBER_PREFIX, '').replace(
     'FieldNumber', 'Specifics').replace(
     'AppNotificationSpecifics', 'AppNotification')