Support nullable types in mojom.

mojo/public/tools/bindings/pylib/mojom/generate/pack.py

 # Copyright 2013 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.
 
 import module as mojom
 
 # This module provides a mechanism for determining the packed order and offsets
 # of a mojom.Struct.
 #
 # ps = pack.PackedStruct(struct)
@@ skipping 16 matching lines @@
     mojom.DCPIPE:       4,
     mojom.DPPIPE:       4,
     mojom.INT64:        8,
     mojom.UINT64:       8,
     mojom.DOUBLE:       8,
     mojom.STRING:       8
   }
 
   @classmethod
   def GetSizeForKind(cls, kind):
+    if isinstance(kind, mojom.Nullable):
+      return cls.GetSizeForKind(kind.kind)
     if isinstance(kind, (mojom.Array, mojom.Struct, mojom.FixedArray)):
       return 8
     if isinstance(kind, mojom.Interface) or \
        isinstance(kind, mojom.InterfaceRequest):
       kind = mojom.MSGPIPE
     if isinstance(kind, mojom.Enum):
       # TODO(mpcomplete): what about big enums?
       return cls.kind_to_size[mojom.INT32]
     if not kind in cls.kind_to_size:
       raise Exception("Invalid kind: %s" % kind.spec)
@@ skipping 94 matching lines @@
     limit_of_previous_field = packed_field.offset + packed_field.size
 
   for i in xrange(limit_of_previous_field, len(bytes)):
     bytes[i].is_padding = True
 
   for byte in bytes:
     # A given byte cannot both be padding and have a fields packed into it.
     assert not (byte.is_padding and byte.packed_fields)
 
   return bytes