mojo: Allow circular dependencies between structs

mojo/public/tools/bindings/generators/mojom_python_generator.py

 # Copyright 2014 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.
 
 """Generates Python source files from a mojom.Module."""
 
 import re
 from itertools import ifilter
 
 import mojom.generate.generator as generator
@@ skipping 128 matching lines @@
     if mojom.IsFixedArrayKind(kind):
       arguments.append('length=%d' % kind.length)
     array_type = 'GenericArrayType'
     if kind.kind == mojom.BOOL:
       array_type = 'BooleanArrayType'
     elif kind.kind in _kind_to_typecode_for_native_array:
       array_type = 'NativeArrayType'
     return '_descriptor.%s(%s)' % (array_type, ', '.join(arguments))
 
   if mojom.IsStructKind(kind):
-    arguments = [ GetStructClass(kind) ]
+    arguments = [ 'lambda: %s' % GetStructClass(kind) ]
     if mojom.IsNullableKind(kind):
       arguments.append('nullable=True')
     return '_descriptor.StructType(%s)' % ', '.join(arguments)
 
   if mojom.IsEnumKind(kind):
     return GetFieldType(mojom.INT32)
 
   return _kind_to_type.get(kind, '_descriptor.TYPE_NONE')
 
 def GetFieldDescriptor(packed_field):
@@ skipping 122 matching lines @@
   def GetImports(self):
     for each in self.module.imports:
       each['python_module'] = each['module_name'].replace('.mojom', '_mojom')
     return self.module.imports
 
   def GetJinjaParameters(self):
     return {
       'lstrip_blocks': True,
       'trim_blocks': True,
     }