diff --git a/scripts/update_metadata_pb2.py b/scripts/update_metadata_pb2.py
index 3cf2a0b..cb6c39c 100644
--- a/scripts/update_metadata_pb2.py
+++ b/scripts/update_metadata_pb2.py
@@ -20,7 +20,7 @@
   package='chromeos_update_engine',
   syntax='proto2',
   serialized_options=_b('H\003'),
-  serialized_pb=_b('\n\x15update_metadata.proto\x12\x16\x63hromeos_update_engine\"1\n\x06\x45xtent\x12\x13\n\x0bstart_block\x18\x01 \x01(\x04\x12\x12\n\nnum_blocks\x18\x02 \x01(\x04\"\x9f\x01\n\nSignatures\x12@\n\nsignatures\x18\x01 \x03(\x0b\x32,.chromeos_update_engine.Signatures.Signature\x1aO\n\tSignature\x12\x13\n\x07version\x18\x01 \x01(\rB\x02\x18\x01\x12\x0c\n\x04\x64\x61ta\x18\x02 \x01(\x0c\x12\x1f\n\x17unpadded_signature_size\x18\x03 \x01(\x07\"+\n\rPartitionInfo\x12\x0c\n\x04size\x18\x01 \x01(\x04\x12\x0c\n\x04hash\x18\x02 \x01(\x0c\"\xa6\x04\n\x10InstallOperation\x12;\n\x04type\x18\x01 \x02(\x0e\x32-.chromeos_update_engine.InstallOperation.Type\x12\x13\n\x0b\x64\x61ta_offset\x18\x02 \x01(\x04\x12\x13\n\x0b\x64\x61ta_length\x18\x03 \x01(\x04\x12\x33\n\x0bsrc_extents\x18\x04 \x03(\x0b\x32\x1e.chromeos_update_engine.Extent\x12\x12\n\nsrc_length\x18\x05 \x01(\x04\x12\x33\n\x0b\x64st_extents\x18\x06 \x03(\x0b\x32\x1e.chromeos_update_engine.Extent\x12\x12\n\ndst_length\x18\x07 \x01(\x04\x12\x18\n\x10\x64\x61ta_sha256_hash\x18\x08 \x01(\x0c\x12\x17\n\x0fsrc_sha256_hash\x18\t \x01(\x0c\"\xe5\x01\n\x04Type\x12\x0b\n\x07REPLACE\x10\x00\x12\x0e\n\nREPLACE_BZ\x10\x01\x12\x0c\n\x04MOVE\x10\x02\x1a\x02\x08\x01\x12\x0e\n\x06\x42SDIFF\x10\x03\x1a\x02\x08\x01\x12\x0f\n\x0bSOURCE_COPY\x10\x04\x12\x11\n\rSOURCE_BSDIFF\x10\x05\x12\x0e\n\nREPLACE_XZ\x10\x08\x12\x08\n\x04ZERO\x10\x06\x12\x0b\n\x07\x44ISCARD\x10\x07\x12\x11\n\rBROTLI_BSDIFF\x10\n\x12\x0c\n\x08PUFFDIFF\x10\t\x12\x0c\n\x08ZUCCHINI\x10\x0b\x12\x12\n\x0eLZ4DIFF_BSDIFF\x10\x0c\x12\x14\n\x10LZ4DIFF_PUFFDIFF\x10\r\"\x81\x02\n\x11\x43owMergeOperation\x12<\n\x04type\x18\x01 \x01(\x0e\x32..chromeos_update_engine.CowMergeOperation.Type\x12\x32\n\nsrc_extent\x18\x02 \x01(\x0b\x32\x1e.chromeos_update_engine.Extent\x12\x32\n\ndst_extent\x18\x03 \x01(\x0b\x32\x1e.chromeos_update_engine.Extent\x12\x12\n\nsrc_offset\x18\x04 \x01(\r\"2\n\x04Type\x12\x0c\n\x08\x43OW_COPY\x10\x00\x12\x0b\n\x07\x43OW_XOR\x10\x01\x12\x0f\n\x0b\x43OW_REPLACE\x10\x02\"\xc8\x06\n\x0fPartitionUpdate\x12\x16\n\x0epartition_name\x18\x01 \x02(\t\x12\x17\n\x0frun_postinstall\x18\x02 \x01(\x08\x12\x18\n\x10postinstall_path\x18\x03 \x01(\t\x12\x17\n\x0f\x66ilesystem_type\x18\x04 \x01(\t\x12M\n\x17new_partition_signature\x18\x05 \x03(\x0b\x32,.chromeos_update_engine.Signatures.Signature\x12\x41\n\x12old_partition_info\x18\x06 \x01(\x0b\x32%.chromeos_update_engine.PartitionInfo\x12\x41\n\x12new_partition_info\x18\x07 \x01(\x0b\x32%.chromeos_update_engine.PartitionInfo\x12<\n\noperations\x18\x08 \x03(\x0b\x32(.chromeos_update_engine.InstallOperation\x12\x1c\n\x14postinstall_optional\x18\t \x01(\x08\x12=\n\x15hash_tree_data_extent\x18\n \x01(\x0b\x32\x1e.chromeos_update_engine.Extent\x12\x38\n\x10hash_tree_extent\x18\x0b \x01(\x0b\x32\x1e.chromeos_update_engine.Extent\x12\x1b\n\x13hash_tree_algorithm\x18\x0c \x01(\t\x12\x16\n\x0ehash_tree_salt\x18\r \x01(\x0c\x12\x37\n\x0f\x66\x65\x63_data_extent\x18\x0e \x01(\x0b\x32\x1e.chromeos_update_engine.Extent\x12\x32\n\nfec_extent\x18\x0f \x01(\x0b\x32\x1e.chromeos_update_engine.Extent\x12\x14\n\tfec_roots\x18\x10 \x01(\r:\x01\x32\x12\x0f\n\x07version\x18\x11 \x01(\t\x12\x43\n\x10merge_operations\x18\x12 \x03(\x0b\x32).chromeos_update_engine.CowMergeOperation\x12\x19\n\x11\x65stimate_cow_size\x18\x13 \x01(\x04\"L\n\x15\x44ynamicPartitionGroup\x12\x0c\n\x04name\x18\x01 \x02(\t\x12\x0c\n\x04size\x18\x02 \x01(\x04\x12\x17\n\x0fpartition_names\x18\x03 \x03(\t\"\xbe\x01\n\x18\x44ynamicPartitionMetadata\x12=\n\x06groups\x18\x01 \x03(\x0b\x32-.chromeos_update_engine.DynamicPartitionGroup\x12\x18\n\x10snapshot_enabled\x18\x02 \x01(\x08\x12\x14\n\x0cvabc_enabled\x18\x03 \x01(\x08\x12\x1e\n\x16vabc_compression_param\x18\x04 \x01(\t\x12\x13\n\x0b\x63ow_version\x18\x05 \x01(\r\"c\n\x08\x41pexInfo\x12\x14\n\x0cpackage_name\x18\x01 \x01(\t\x12\x0f\n\x07version\x18\x02 \x01(\x03\x12\x15\n\ris_compressed\x18\x03 \x01(\x08\x12\x19\n\x11\x64\x65\x63ompressed_size\x18\x04 \x01(\x03\"C\n\x0c\x41pexMetadata\x12\x33\n\tapex_info\x18\x01 \x03(\x0b\x32 .chromeos_update_engine.ApexInfo\"\xc3\x03\n\x14\x44\x65ltaArchiveManifest\x12\x18\n\nblock_size\x18\x03 \x01(\r:\x04\x34\x30\x39\x36\x12\x19\n\x11signatures_offset\x18\x04 \x01(\x04\x12\x17\n\x0fsignatures_size\x18\x05 \x01(\x04\x12\x18\n\rminor_version\x18\x0c \x01(\r:\x01\x30\x12;\n\npartitions\x18\r \x03(\x0b\x32\'.chromeos_update_engine.PartitionUpdate\x12\x15\n\rmax_timestamp\x18\x0e \x01(\x03\x12T\n\x1a\x64ynamic_partition_metadata\x18\x0f \x01(\x0b\x32\x30.chromeos_update_engine.DynamicPartitionMetadata\x12\x16\n\x0epartial_update\x18\x10 \x01(\x08\x12\x33\n\tapex_info\x18\x11 \x03(\x0b\x32 .chromeos_update_engine.ApexInfo\x12\x1c\n\x14security_patch_level\x18\x12 \x01(\tJ\x04\x08\x01\x10\x02J\x04\x08\x02\x10\x03J\x04\x08\x06\x10\x07J\x04\x08\x07\x10\x08J\x04\x08\x08\x10\tJ\x04\x08\t\x10\nJ\x04\x08\n\x10\x0bJ\x04\x08\x0b\x10\x0c\x42\x02H\x03')
+  serialized_pb=_b('\n\x15update_metadata.proto\x12\x16\x63hromeos_update_engine\"1\n\x06\x45xtent\x12\x13\n\x0bstart_block\x18\x01 \x01(\x04\x12\x12\n\nnum_blocks\x18\x02 \x01(\x04\"\x9f\x01\n\nSignatures\x12@\n\nsignatures\x18\x01 \x03(\x0b\x32,.chromeos_update_engine.Signatures.Signature\x1aO\n\tSignature\x12\x13\n\x07version\x18\x01 \x01(\rB\x02\x18\x01\x12\x0c\n\x04\x64\x61ta\x18\x02 \x01(\x0c\x12\x1f\n\x17unpadded_signature_size\x18\x03 \x01(\x07\"+\n\rPartitionInfo\x12\x0c\n\x04size\x18\x01 \x01(\x04\x12\x0c\n\x04hash\x18\x02 \x01(\x0c\"\xa6\x04\n\x10InstallOperation\x12;\n\x04type\x18\x01 \x02(\x0e\x32-.chromeos_update_engine.InstallOperation.Type\x12\x13\n\x0b\x64\x61ta_offset\x18\x02 \x01(\x04\x12\x13\n\x0b\x64\x61ta_length\x18\x03 \x01(\x04\x12\x33\n\x0bsrc_extents\x18\x04 \x03(\x0b\x32\x1e.chromeos_update_engine.Extent\x12\x12\n\nsrc_length\x18\x05 \x01(\x04\x12\x33\n\x0b\x64st_extents\x18\x06 \x03(\x0b\x32\x1e.chromeos_update_engine.Extent\x12\x12\n\ndst_length\x18\x07 \x01(\x04\x12\x18\n\x10\x64\x61ta_sha256_hash\x18\x08 \x01(\x0c\x12\x17\n\x0fsrc_sha256_hash\x18\t \x01(\x0c\"\xe5\x01\n\x04Type\x12\x0b\n\x07REPLACE\x10\x00\x12\x0e\n\nREPLACE_BZ\x10\x01\x12\x0c\n\x04MOVE\x10\x02\x1a\x02\x08\x01\x12\x0e\n\x06\x42SDIFF\x10\x03\x1a\x02\x08\x01\x12\x0f\n\x0bSOURCE_COPY\x10\x04\x12\x11\n\rSOURCE_BSDIFF\x10\x05\x12\x0e\n\nREPLACE_XZ\x10\x08\x12\x08\n\x04ZERO\x10\x06\x12\x0b\n\x07\x44ISCARD\x10\x07\x12\x11\n\rBROTLI_BSDIFF\x10\n\x12\x0c\n\x08PUFFDIFF\x10\t\x12\x0c\n\x08ZUCCHINI\x10\x0b\x12\x12\n\x0eLZ4DIFF_BSDIFF\x10\x0c\x12\x14\n\x10LZ4DIFF_PUFFDIFF\x10\r\"\x81\x02\n\x11\x43owMergeOperation\x12<\n\x04type\x18\x01 \x01(\x0e\x32..chromeos_update_engine.CowMergeOperation.Type\x12\x32\n\nsrc_extent\x18\x02 \x01(\x0b\x32\x1e.chromeos_update_engine.Extent\x12\x32\n\ndst_extent\x18\x03 \x01(\x0b\x32\x1e.chromeos_update_engine.Extent\x12\x12\n\nsrc_offset\x18\x04 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\x01(\t\x12\x16\n\x0ehash_tree_salt\x18\r \x01(\x0c\x12\x37\n\x0f\x66\x65\x63_data_extent\x18\x0e \x01(\x0b\x32\x1e.chromeos_update_engine.Extent\x12\x32\n\nfec_extent\x18\x0f \x01(\x0b\x32\x1e.chromeos_update_engine.Extent\x12\x14\n\tfec_roots\x18\x10 \x01(\r:\x01\x32\x12\x0f\n\x07version\x18\x11 \x01(\t\x12\x43\n\x10merge_operations\x18\x12 \x03(\x0b\x32).chromeos_update_engine.CowMergeOperation\x12\x19\n\x11\x65stimate_cow_size\x18\x13 \x01(\x04\"L\n\x15\x44ynamicPartitionGroup\x12\x0c\n\x04name\x18\x01 \x02(\t\x12\x0c\n\x04size\x18\x02 \x01(\x04\x12\x17\n\x0fpartition_names\x18\x03 \x03(\t\"8\n\x0eVABCFeatureSet\x12\x10\n\x08threaded\x18\x01 \x01(\x08\x12\x14\n\x0c\x62\x61tch_writes\x18\x02 \x01(\x08\"\x80\x02\n\x18\x44ynamicPartitionMetadata\x12=\n\x06groups\x18\x01 \x03(\x0b\x32-.chromeos_update_engine.DynamicPartitionGroup\x12\x18\n\x10snapshot_enabled\x18\x02 \x01(\x08\x12\x14\n\x0cvabc_enabled\x18\x03 \x01(\x08\x12\x1e\n\x16vabc_compression_param\x18\x04 \x01(\t\x12\x13\n\x0b\x63ow_version\x18\x05 \x01(\r\x12@\n\x10vabc_feature_set\x18\x06 \x01(\x0b\x32&.chromeos_update_engine.VABCFeatureSet\"c\n\x08\x41pexInfo\x12\x14\n\x0cpackage_name\x18\x01 \x01(\t\x12\x0f\n\x07version\x18\x02 \x01(\x03\x12\x15\n\ris_compressed\x18\x03 \x01(\x08\x12\x19\n\x11\x64\x65\x63ompressed_size\x18\x04 \x01(\x03\"C\n\x0c\x41pexMetadata\x12\x33\n\tapex_info\x18\x01 \x03(\x0b\x32 .chromeos_update_engine.ApexInfo\"\xc3\x03\n\x14\x44\x65ltaArchiveManifest\x12\x18\n\nblock_size\x18\x03 \x01(\r:\x04\x34\x30\x39\x36\x12\x19\n\x11signatures_offset\x18\x04 \x01(\x04\x12\x17\n\x0fsignatures_size\x18\x05 \x01(\x04\x12\x18\n\rminor_version\x18\x0c \x01(\r:\x01\x30\x12;\n\npartitions\x18\r \x03(\x0b\x32\'.chromeos_update_engine.PartitionUpdate\x12\x15\n\rmax_timestamp\x18\x0e \x01(\x03\x12T\n\x1a\x64ynamic_partition_metadata\x18\x0f \x01(\x0b\x32\x30.chromeos_update_engine.DynamicPartitionMetadata\x12\x16\n\x0epartial_update\x18\x10 \x01(\x08\x12\x33\n\tapex_info\x18\x11 \x03(\x0b\x32 .chromeos_update_engine.ApexInfo\x12\x1c\n\x14security_patch_level\x18\x12 \x01(\tJ\x04\x08\x01\x10\x02J\x04\x08\x02\x10\x03J\x04\x08\x06\x10\x07J\x04\x08\x07\x10\x08J\x04\x08\x08\x10\tJ\x04\x08\t\x10\nJ\x04\x08\n\x10\x0bJ\x04\x08\x0b\x10\x0c\x42\x02H\x03')
 )
 
 
@@ -616,6 +616,44 @@
 )
 
 
+_VABCFEATURESET = _descriptor.Descriptor(
+  name='VABCFeatureSet',
+  full_name='chromeos_update_engine.VABCFeatureSet',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='threaded', full_name='chromeos_update_engine.VABCFeatureSet.threaded', index=0,
+      number=1, type=8, cpp_type=7, label=1,
+      has_default_value=False, default_value=False,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      serialized_options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='batch_writes', full_name='chromeos_update_engine.VABCFeatureSet.batch_writes', index=1,
+      number=2, type=8, cpp_type=7, label=1,
+      has_default_value=False, default_value=False,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      serialized_options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  serialized_options=None,
+  is_extendable=False,
+  syntax='proto2',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=2041,
+  serialized_end=2097,
+)
+
+
 _DYNAMICPARTITIONMETADATA = _descriptor.Descriptor(
   name='DynamicPartitionMetadata',
   full_name='chromeos_update_engine.DynamicPartitionMetadata',
@@ -658,6 +696,13 @@
       message_type=None, enum_type=None, containing_type=None,
       is_extension=False, extension_scope=None,
       serialized_options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='vabc_feature_set', full_name='chromeos_update_engine.DynamicPartitionMetadata.vabc_feature_set', index=5,
+      number=6, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      serialized_options=None, file=DESCRIPTOR),
   ],
   extensions=[
   ],
@@ -670,8 +715,8 @@
   extension_ranges=[],
   oneofs=[
   ],
-  serialized_start=2042,
-  serialized_end=2232,
+  serialized_start=2100,
+  serialized_end=2356,
 )
 
 
@@ -722,8 +767,8 @@
   extension_ranges=[],
   oneofs=[
   ],
-  serialized_start=2234,
-  serialized_end=2333,
+  serialized_start=2358,
+  serialized_end=2457,
 )
 
 
@@ -753,8 +798,8 @@
   extension_ranges=[],
   oneofs=[
   ],
-  serialized_start=2335,
-  serialized_end=2402,
+  serialized_start=2459,
+  serialized_end=2526,
 )
 
 
@@ -847,8 +892,8 @@
   extension_ranges=[],
   oneofs=[
   ],
-  serialized_start=2405,
-  serialized_end=2856,
+  serialized_start=2529,
+  serialized_end=2980,
 )
 
 _SIGNATURES_SIGNATURE.containing_type = _SIGNATURES
@@ -871,6 +916,7 @@
 _PARTITIONUPDATE.fields_by_name['fec_extent'].message_type = _EXTENT
 _PARTITIONUPDATE.fields_by_name['merge_operations'].message_type = _COWMERGEOPERATION
 _DYNAMICPARTITIONMETADATA.fields_by_name['groups'].message_type = _DYNAMICPARTITIONGROUP
+_DYNAMICPARTITIONMETADATA.fields_by_name['vabc_feature_set'].message_type = _VABCFEATURESET
 _APEXMETADATA.fields_by_name['apex_info'].message_type = _APEXINFO
 _DELTAARCHIVEMANIFEST.fields_by_name['partitions'].message_type = _PARTITIONUPDATE
 _DELTAARCHIVEMANIFEST.fields_by_name['dynamic_partition_metadata'].message_type = _DYNAMICPARTITIONMETADATA
@@ -882,6 +928,7 @@
 DESCRIPTOR.message_types_by_name['CowMergeOperation'] = _COWMERGEOPERATION
 DESCRIPTOR.message_types_by_name['PartitionUpdate'] = _PARTITIONUPDATE
 DESCRIPTOR.message_types_by_name['DynamicPartitionGroup'] = _DYNAMICPARTITIONGROUP
+DESCRIPTOR.message_types_by_name['VABCFeatureSet'] = _VABCFEATURESET
 DESCRIPTOR.message_types_by_name['DynamicPartitionMetadata'] = _DYNAMICPARTITIONMETADATA
 DESCRIPTOR.message_types_by_name['ApexInfo'] = _APEXINFO
 DESCRIPTOR.message_types_by_name['ApexMetadata'] = _APEXMETADATA
@@ -945,6 +992,13 @@
   })
 _sym_db.RegisterMessage(DynamicPartitionGroup)
 
+VABCFeatureSet = _reflection.GeneratedProtocolMessageType('VABCFeatureSet', (_message.Message,), {
+  'DESCRIPTOR' : _VABCFEATURESET,
+  '__module__' : 'update_metadata_pb2'
+  # @@protoc_insertion_point(class_scope:chromeos_update_engine.VABCFeatureSet)
+  })
+_sym_db.RegisterMessage(VABCFeatureSet)
+
 DynamicPartitionMetadata = _reflection.GeneratedProtocolMessageType('DynamicPartitionMetadata', (_message.Message,), {
   'DESCRIPTOR' : _DYNAMICPARTITIONMETADATA,
   '__module__' : 'update_metadata_pb2'