diff --git a/scripts/update_payload/update_metadata_pb2.py b/scripts/update_payload/update_metadata_pb2.py
index 383ec6f..08fffdf 100644
--- a/scripts/update_payload/update_metadata_pb2.py
+++ b/scripts/update_payload/update_metadata_pb2.py
@@ -1,26 +1,19 @@
 # Generated by the protocol buffer compiler.  DO NOT EDIT!
 # source: update_metadata.proto
 
-import sys
-_b=sys.version_info[0]<3 and (lambda x:x) or (lambda x:x.encode('latin1'))
 from google.protobuf import descriptor as _descriptor
 from google.protobuf import message as _message
 from google.protobuf import reflection as _reflection
-from google.protobuf import symbol_database as _symbol_database
 from google.protobuf import descriptor_pb2
 # @@protoc_insertion_point(imports)
 
-_sym_db = _symbol_database.Default()
-
 
 
 
 DESCRIPTOR = _descriptor.FileDescriptor(
   name='update_metadata.proto',
   package='chromeos_update_engine',
-  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\"z\n\nSignatures\x12@\n\nsignatures\x18\x01 \x03(\x0b\x32,.chromeos_update_engine.Signatures.Signature\x1a*\n\tSignature\x12\x0f\n\x07version\x18\x01 \x01(\r\x12\x0c\n\x04\x64\x61ta\x18\x02 \x01(\x0c\"+\n\rPartitionInfo\x12\x0c\n\x04size\x18\x01 \x01(\x04\x12\x0c\n\x04hash\x18\x02 \x01(\x0c\"w\n\tImageInfo\x12\r\n\x05\x62oard\x18\x01 \x01(\t\x12\x0b\n\x03key\x18\x02 \x01(\t\x12\x0f\n\x07\x63hannel\x18\x03 \x01(\t\x12\x0f\n\x07version\x18\x04 \x01(\t\x12\x15\n\rbuild_channel\x18\x05 \x01(\t\x12\x15\n\rbuild_version\x18\x06 \x01(\t\"\xc5\x03\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(\r\x12\x13\n\x0b\x64\x61ta_length\x18\x03 \x01(\r\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\"\x84\x01\n\x04Type\x12\x0b\n\x07REPLACE\x10\x00\x12\x0e\n\nREPLACE_BZ\x10\x01\x12\x08\n\x04MOVE\x10\x02\x12\n\n\x06\x42SDIFF\x10\x03\x12\x0f\n\x0bSOURCE_COPY\x10\x04\x12\x11\n\rSOURCE_BSDIFF\x10\x05\x12\x08\n\x04ZERO\x10\x06\x12\x0b\n\x07\x44ISCARD\x10\x07\x12\x0e\n\nREPLACE_XZ\x10\x08\"\xd5\x02\n\x0fPartitionUpdate\x12\x16\n\x0epartition_name\x18\x01 \x02(\t\x12\x17\n\x0frun_postinstall\x18\x02 \x01(\x08\x12M\n\x17new_partition_signature\x18\x03 \x03(\x0b\x32,.chromeos_update_engine.Signatures.Signature\x12\x41\n\x12old_partition_info\x18\x04 \x01(\x0b\x32%.chromeos_update_engine.PartitionInfo\x12\x41\n\x12new_partition_info\x18\x05 \x01(\x0b\x32%.chromeos_update_engine.PartitionInfo\x12<\n\noperations\x18\x06 \x03(\x0b\x32(.chromeos_update_engine.InstallOperation\"\xc4\x05\n\x14\x44\x65ltaArchiveManifest\x12\x44\n\x12install_operations\x18\x01 \x03(\x0b\x32(.chromeos_update_engine.InstallOperation\x12K\n\x19kernel_install_operations\x18\x02 \x03(\x0b\x32(.chromeos_update_engine.InstallOperation\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>\n\x0fold_kernel_info\x18\x06 \x01(\x0b\x32%.chromeos_update_engine.PartitionInfo\x12>\n\x0fnew_kernel_info\x18\x07 \x01(\x0b\x32%.chromeos_update_engine.PartitionInfo\x12>\n\x0fold_rootfs_info\x18\x08 \x01(\x0b\x32%.chromeos_update_engine.PartitionInfo\x12>\n\x0fnew_rootfs_info\x18\t \x01(\x0b\x32%.chromeos_update_engine.PartitionInfo\x12\x39\n\x0eold_image_info\x18\n \x01(\x0b\x32!.chromeos_update_engine.ImageInfo\x12\x39\n\x0enew_image_info\x18\x0b \x01(\x0b\x32!.chromeos_update_engine.ImageInfo\x12\x18\n\rminor_version\x18\x0c \x01(\r:\x01\x30\x12;\n\npartitions\x18\r \x03(\x0b\x32\'.chromeos_update_engine.PartitionUpdateB\x02H\x03')
-)
-_sym_db.RegisterFileDescriptor(DESCRIPTOR)
+  serialized_pb='\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\"z\n\nSignatures\x12@\n\nsignatures\x18\x01 \x03(\x0b\x32,.chromeos_update_engine.Signatures.Signature\x1a*\n\tSignature\x12\x0f\n\x07version\x18\x01 \x01(\r\x12\x0c\n\x04\x64\x61ta\x18\x02 \x01(\x0c\"+\n\rPartitionInfo\x12\x0c\n\x04size\x18\x01 \x01(\x04\x12\x0c\n\x04hash\x18\x02 \x01(\x0c\"w\n\tImageInfo\x12\r\n\x05\x62oard\x18\x01 \x01(\t\x12\x0b\n\x03key\x18\x02 \x01(\t\x12\x0f\n\x07\x63hannel\x18\x03 \x01(\t\x12\x0f\n\x07version\x18\x04 \x01(\t\x12\x15\n\rbuild_channel\x18\x05 \x01(\t\x12\x15\n\rbuild_version\x18\x06 \x01(\t\"\xc5\x03\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(\r\x12\x13\n\x0b\x64\x61ta_length\x18\x03 \x01(\r\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\"\x84\x01\n\x04Type\x12\x0b\n\x07REPLACE\x10\x00\x12\x0e\n\nREPLACE_BZ\x10\x01\x12\x08\n\x04MOVE\x10\x02\x12\n\n\x06\x42SDIFF\x10\x03\x12\x0f\n\x0bSOURCE_COPY\x10\x04\x12\x11\n\rSOURCE_BSDIFF\x10\x05\x12\x08\n\x04ZERO\x10\x06\x12\x0b\n\x07\x44ISCARD\x10\x07\x12\x0e\n\nREPLACE_XZ\x10\x08\"\xd5\x02\n\x0fPartitionUpdate\x12\x16\n\x0epartition_name\x18\x01 \x02(\t\x12\x17\n\x0frun_postinstall\x18\x02 \x01(\x08\x12M\n\x17new_partition_signature\x18\x03 \x03(\x0b\x32,.chromeos_update_engine.Signatures.Signature\x12\x41\n\x12old_partition_info\x18\x04 \x01(\x0b\x32%.chromeos_update_engine.PartitionInfo\x12\x41\n\x12new_partition_info\x18\x05 \x01(\x0b\x32%.chromeos_update_engine.PartitionInfo\x12<\n\noperations\x18\x06 \x03(\x0b\x32(.chromeos_update_engine.InstallOperation\"\xc4\x05\n\x14\x44\x65ltaArchiveManifest\x12\x44\n\x12install_operations\x18\x01 \x03(\x0b\x32(.chromeos_update_engine.InstallOperation\x12K\n\x19kernel_install_operations\x18\x02 \x03(\x0b\x32(.chromeos_update_engine.InstallOperation\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>\n\x0fold_kernel_info\x18\x06 \x01(\x0b\x32%.chromeos_update_engine.PartitionInfo\x12>\n\x0fnew_kernel_info\x18\x07 \x01(\x0b\x32%.chromeos_update_engine.PartitionInfo\x12>\n\x0fold_rootfs_info\x18\x08 \x01(\x0b\x32%.chromeos_update_engine.PartitionInfo\x12>\n\x0fnew_rootfs_info\x18\t \x01(\x0b\x32%.chromeos_update_engine.PartitionInfo\x12\x39\n\x0eold_image_info\x18\n \x01(\x0b\x32!.chromeos_update_engine.ImageInfo\x12\x39\n\x0enew_image_info\x18\x0b \x01(\x0b\x32!.chromeos_update_engine.ImageInfo\x12\x18\n\rminor_version\x18\x0c \x01(\r:\x01\x30\x12;\n\npartitions\x18\r \x03(\x0b\x32\'.chromeos_update_engine.PartitionUpdateB\x02H\x03')
 
 
 
@@ -72,7 +65,6 @@
   serialized_start=712,
   serialized_end=844,
 )
-_sym_db.RegisterEnumDescriptor(_INSTALLOPERATION_TYPE)
 
 
 _EXTENT = _descriptor.Descriptor(
@@ -105,8 +97,6 @@
   options=None,
   is_extendable=False,
   extension_ranges=[],
-  oneofs=[
-  ],
   serialized_start=49,
   serialized_end=98,
 )
@@ -129,7 +119,7 @@
     _descriptor.FieldDescriptor(
       name='data', full_name='chromeos_update_engine.Signatures.Signature.data', index=1,
       number=2, type=12, cpp_type=9, label=1,
-      has_default_value=False, default_value=_b(""),
+      has_default_value=False, default_value="",
       message_type=None, enum_type=None, containing_type=None,
       is_extension=False, extension_scope=None,
       options=None),
@@ -142,8 +132,6 @@
   options=None,
   is_extendable=False,
   extension_ranges=[],
-  oneofs=[
-  ],
   serialized_start=180,
   serialized_end=222,
 )
@@ -171,8 +159,6 @@
   options=None,
   is_extendable=False,
   extension_ranges=[],
-  oneofs=[
-  ],
   serialized_start=100,
   serialized_end=222,
 )
@@ -195,7 +181,7 @@
     _descriptor.FieldDescriptor(
       name='hash', full_name='chromeos_update_engine.PartitionInfo.hash', index=1,
       number=2, type=12, cpp_type=9, label=1,
-      has_default_value=False, default_value=_b(""),
+      has_default_value=False, default_value="",
       message_type=None, enum_type=None, containing_type=None,
       is_extension=False, extension_scope=None,
       options=None),
@@ -208,8 +194,6 @@
   options=None,
   is_extendable=False,
   extension_ranges=[],
-  oneofs=[
-  ],
   serialized_start=224,
   serialized_end=267,
 )
@@ -225,42 +209,42 @@
     _descriptor.FieldDescriptor(
       name='board', full_name='chromeos_update_engine.ImageInfo.board', index=0,
       number=1, type=9, cpp_type=9, label=1,
-      has_default_value=False, default_value=_b("").decode('utf-8'),
+      has_default_value=False, default_value=unicode("", "utf-8"),
       message_type=None, enum_type=None, containing_type=None,
       is_extension=False, extension_scope=None,
       options=None),
     _descriptor.FieldDescriptor(
       name='key', full_name='chromeos_update_engine.ImageInfo.key', index=1,
       number=2, type=9, cpp_type=9, label=1,
-      has_default_value=False, default_value=_b("").decode('utf-8'),
+      has_default_value=False, default_value=unicode("", "utf-8"),
       message_type=None, enum_type=None, containing_type=None,
       is_extension=False, extension_scope=None,
       options=None),
     _descriptor.FieldDescriptor(
       name='channel', full_name='chromeos_update_engine.ImageInfo.channel', index=2,
       number=3, type=9, cpp_type=9, label=1,
-      has_default_value=False, default_value=_b("").decode('utf-8'),
+      has_default_value=False, default_value=unicode("", "utf-8"),
       message_type=None, enum_type=None, containing_type=None,
       is_extension=False, extension_scope=None,
       options=None),
     _descriptor.FieldDescriptor(
       name='version', full_name='chromeos_update_engine.ImageInfo.version', index=3,
       number=4, type=9, cpp_type=9, label=1,
-      has_default_value=False, default_value=_b("").decode('utf-8'),
+      has_default_value=False, default_value=unicode("", "utf-8"),
       message_type=None, enum_type=None, containing_type=None,
       is_extension=False, extension_scope=None,
       options=None),
     _descriptor.FieldDescriptor(
       name='build_channel', full_name='chromeos_update_engine.ImageInfo.build_channel', index=4,
       number=5, type=9, cpp_type=9, label=1,
-      has_default_value=False, default_value=_b("").decode('utf-8'),
+      has_default_value=False, default_value=unicode("", "utf-8"),
       message_type=None, enum_type=None, containing_type=None,
       is_extension=False, extension_scope=None,
       options=None),
     _descriptor.FieldDescriptor(
       name='build_version', full_name='chromeos_update_engine.ImageInfo.build_version', index=5,
       number=6, type=9, cpp_type=9, label=1,
-      has_default_value=False, default_value=_b("").decode('utf-8'),
+      has_default_value=False, default_value=unicode("", "utf-8"),
       message_type=None, enum_type=None, containing_type=None,
       is_extension=False, extension_scope=None,
       options=None),
@@ -273,8 +257,6 @@
   options=None,
   is_extendable=False,
   extension_ranges=[],
-  oneofs=[
-  ],
   serialized_start=269,
   serialized_end=388,
 )
@@ -339,14 +321,14 @@
     _descriptor.FieldDescriptor(
       name='data_sha256_hash', full_name='chromeos_update_engine.InstallOperation.data_sha256_hash', index=7,
       number=8, type=12, cpp_type=9, label=1,
-      has_default_value=False, default_value=_b(""),
+      has_default_value=False, default_value="",
       message_type=None, enum_type=None, containing_type=None,
       is_extension=False, extension_scope=None,
       options=None),
     _descriptor.FieldDescriptor(
       name='src_sha256_hash', full_name='chromeos_update_engine.InstallOperation.src_sha256_hash', index=8,
       number=9, type=12, cpp_type=9, label=1,
-      has_default_value=False, default_value=_b(""),
+      has_default_value=False, default_value="",
       message_type=None, enum_type=None, containing_type=None,
       is_extension=False, extension_scope=None,
       options=None),
@@ -360,8 +342,6 @@
   options=None,
   is_extendable=False,
   extension_ranges=[],
-  oneofs=[
-  ],
   serialized_start=391,
   serialized_end=844,
 )
@@ -377,7 +357,7 @@
     _descriptor.FieldDescriptor(
       name='partition_name', full_name='chromeos_update_engine.PartitionUpdate.partition_name', index=0,
       number=1, type=9, cpp_type=9, label=2,
-      has_default_value=False, default_value=_b("").decode('utf-8'),
+      has_default_value=False, default_value=unicode("", "utf-8"),
       message_type=None, enum_type=None, containing_type=None,
       is_extension=False, extension_scope=None,
       options=None),
@@ -425,8 +405,6 @@
   options=None,
   is_extendable=False,
   extension_ranges=[],
-  oneofs=[
-  ],
   serialized_start=847,
   serialized_end=1188,
 )
@@ -539,18 +517,16 @@
   options=None,
   is_extendable=False,
   extension_ranges=[],
-  oneofs=[
-  ],
   serialized_start=1191,
   serialized_end=1899,
 )
 
-_SIGNATURES_SIGNATURE.containing_type = _SIGNATURES
+_SIGNATURES_SIGNATURE.containing_type = _SIGNATURES;
 _SIGNATURES.fields_by_name['signatures'].message_type = _SIGNATURES_SIGNATURE
 _INSTALLOPERATION.fields_by_name['type'].enum_type = _INSTALLOPERATION_TYPE
 _INSTALLOPERATION.fields_by_name['src_extents'].message_type = _EXTENT
 _INSTALLOPERATION.fields_by_name['dst_extents'].message_type = _EXTENT
-_INSTALLOPERATION_TYPE.containing_type = _INSTALLOPERATION
+_INSTALLOPERATION_TYPE.containing_type = _INSTALLOPERATION;
 _PARTITIONUPDATE.fields_by_name['new_partition_signature'].message_type = _SIGNATURES_SIGNATURE
 _PARTITIONUPDATE.fields_by_name['old_partition_info'].message_type = _PARTITIONINFO
 _PARTITIONUPDATE.fields_by_name['new_partition_info'].message_type = _PARTITIONINFO
@@ -572,64 +548,55 @@
 DESCRIPTOR.message_types_by_name['PartitionUpdate'] = _PARTITIONUPDATE
 DESCRIPTOR.message_types_by_name['DeltaArchiveManifest'] = _DELTAARCHIVEMANIFEST
 
-Extent = _reflection.GeneratedProtocolMessageType('Extent', (_message.Message,), dict(
-  DESCRIPTOR = _EXTENT,
-  __module__ = 'update_metadata_pb2'
+class Extent(_message.Message):
+  __metaclass__ = _reflection.GeneratedProtocolMessageType
+  DESCRIPTOR = _EXTENT
+
   # @@protoc_insertion_point(class_scope:chromeos_update_engine.Extent)
-  ))
-_sym_db.RegisterMessage(Extent)
 
-Signatures = _reflection.GeneratedProtocolMessageType('Signatures', (_message.Message,), dict(
+class Signatures(_message.Message):
+  __metaclass__ = _reflection.GeneratedProtocolMessageType
 
-  Signature = _reflection.GeneratedProtocolMessageType('Signature', (_message.Message,), dict(
-    DESCRIPTOR = _SIGNATURES_SIGNATURE,
-    __module__ = 'update_metadata_pb2'
+  class Signature(_message.Message):
+    __metaclass__ = _reflection.GeneratedProtocolMessageType
+    DESCRIPTOR = _SIGNATURES_SIGNATURE
+
     # @@protoc_insertion_point(class_scope:chromeos_update_engine.Signatures.Signature)
-    ))
-  ,
-  DESCRIPTOR = _SIGNATURES,
-  __module__ = 'update_metadata_pb2'
+  DESCRIPTOR = _SIGNATURES
+
   # @@protoc_insertion_point(class_scope:chromeos_update_engine.Signatures)
-  ))
-_sym_db.RegisterMessage(Signatures)
-_sym_db.RegisterMessage(Signatures.Signature)
 
-PartitionInfo = _reflection.GeneratedProtocolMessageType('PartitionInfo', (_message.Message,), dict(
-  DESCRIPTOR = _PARTITIONINFO,
-  __module__ = 'update_metadata_pb2'
+class PartitionInfo(_message.Message):
+  __metaclass__ = _reflection.GeneratedProtocolMessageType
+  DESCRIPTOR = _PARTITIONINFO
+
   # @@protoc_insertion_point(class_scope:chromeos_update_engine.PartitionInfo)
-  ))
-_sym_db.RegisterMessage(PartitionInfo)
 
-ImageInfo = _reflection.GeneratedProtocolMessageType('ImageInfo', (_message.Message,), dict(
-  DESCRIPTOR = _IMAGEINFO,
-  __module__ = 'update_metadata_pb2'
+class ImageInfo(_message.Message):
+  __metaclass__ = _reflection.GeneratedProtocolMessageType
+  DESCRIPTOR = _IMAGEINFO
+
   # @@protoc_insertion_point(class_scope:chromeos_update_engine.ImageInfo)
-  ))
-_sym_db.RegisterMessage(ImageInfo)
 
-InstallOperation = _reflection.GeneratedProtocolMessageType('InstallOperation', (_message.Message,), dict(
-  DESCRIPTOR = _INSTALLOPERATION,
-  __module__ = 'update_metadata_pb2'
+class InstallOperation(_message.Message):
+  __metaclass__ = _reflection.GeneratedProtocolMessageType
+  DESCRIPTOR = _INSTALLOPERATION
+
   # @@protoc_insertion_point(class_scope:chromeos_update_engine.InstallOperation)
-  ))
-_sym_db.RegisterMessage(InstallOperation)
 
-PartitionUpdate = _reflection.GeneratedProtocolMessageType('PartitionUpdate', (_message.Message,), dict(
-  DESCRIPTOR = _PARTITIONUPDATE,
-  __module__ = 'update_metadata_pb2'
+class PartitionUpdate(_message.Message):
+  __metaclass__ = _reflection.GeneratedProtocolMessageType
+  DESCRIPTOR = _PARTITIONUPDATE
+
   # @@protoc_insertion_point(class_scope:chromeos_update_engine.PartitionUpdate)
-  ))
-_sym_db.RegisterMessage(PartitionUpdate)
 
-DeltaArchiveManifest = _reflection.GeneratedProtocolMessageType('DeltaArchiveManifest', (_message.Message,), dict(
-  DESCRIPTOR = _DELTAARCHIVEMANIFEST,
-  __module__ = 'update_metadata_pb2'
+class DeltaArchiveManifest(_message.Message):
+  __metaclass__ = _reflection.GeneratedProtocolMessageType
+  DESCRIPTOR = _DELTAARCHIVEMANIFEST
+
   # @@protoc_insertion_point(class_scope:chromeos_update_engine.DeltaArchiveManifest)
-  ))
-_sym_db.RegisterMessage(DeltaArchiveManifest)
 
 
 DESCRIPTOR.has_options = True
-DESCRIPTOR._options = _descriptor._ParseOptions(descriptor_pb2.FileOptions(), _b('H\003'))
+DESCRIPTOR._options = _descriptor._ParseOptions(descriptor_pb2.FileOptions(), 'H\003')
 # @@protoc_insertion_point(module_scope)