Mojo: Make the mojom bindings generator not exponential in the import depth.

mojo/public/tools/bindings/pylib/mojom/generate/data.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.
 
 # TODO(vtl): "data" is a pretty vague name. Rename it?
 
 import copy
 
 import module as mojom
 
@@ skipping 116 matching lines @@
     kind = mojom.FixedArray(length, KindFromData(kinds, data[colon+1:], scope))
   else:
     kind = mojom.Kind(data)
 
   kinds[data] = kind
   return kind
 
 def KindFromImport(original_kind, imported_from):
   """Used with 'import module' - clones the kind imported from the given
   module's namespace. Only used with Structs, Interfaces and Enums."""
-  kind = copy.deepcopy(original_kind)
+  kind = copy.copy(original_kind)
+  # |shared_definition| is used to store various properties (see
+  # |AddSharedProperty()| in module.py), including |imported_from|. We don't
+  # want the copy to share these with the original, so copy it if necessary.
+  if hasattr(original_kind, 'shared_definition'):
+    kind.shared_definition = copy.copy(original_kind.shared_definition)
   kind.imported_from = imported_from
   return kind
 
 def ImportFromData(module, data):
   import_module = data['module']
 
   import_item = {}
   import_item['module_name'] = import_module.name
   import_item['namespace'] = import_module.namespace
   import_item['module'] = import_module
 
   # Copy the struct kinds from our imports into the current module.
   for kind in import_module.kinds.itervalues():
     if (isinstance(kind, (mojom.Struct, mojom.Enum, mojom.Interface)) and
         kind.imported_from is None):
       kind = KindFromImport(kind, import_item)
       module.kinds[kind.spec] = kind
   # Ditto for values.
   for value in import_module.values.itervalues():
     if value.imported_from is None:
-      value = copy.deepcopy(value)
+      # Values don't have shared definitions (since they're not nullable), so no
+      # need to do anything special.
+      value = copy.copy(value)
       value.imported_from = import_item
       module.values[value.GetSpec()] = value
 
   return import_item
 
 def StructToData(struct):
   return {
     istr(0, 'name'): struct.name,
     istr(1, 'fields'): map(FieldToData, struct.fields)
   }
@@ skipping 196 matching lines @@
 
 def OrderedModuleFromData(data):
   module = ModuleFromData(data)
   for interface in module.interfaces:
     next_ordinal = 0
     for method in interface.methods:
       if method.ordinal is None:
         method.ordinal = next_ordinal
       next_ordinal = method.ordinal + 1
   return module