Create response_parameters as part of mojom

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

Index: mojo/public/bindings/pylib/generate/mojom.py
diff --git a/mojo/public/bindings/pylib/generate/mojom.py b/mojo/public/bindings/pylib/generate/mojom.py
index 7cb7518349601579a34aa38fe8b5d47f357e4cbd..7b44b2efc348ad4bdf0a44a7536e609367aee8cc 100644
--- a/mojo/public/bindings/pylib/generate/mojom.py
+++ b/mojo/public/bindings/pylib/generate/mojom.py
@@ -127,12 +127,20 @@ class Method(object):
     self.name = name
     self.ordinal = ordinal
     self.parameters = []
+    self.response_parameters = None
 
   def AddParameter(self, name, kind, ordinal = None, default = None):
     parameter = Parameter(name, kind, ordinal, default)
     self.parameters.append(parameter)
     return parameter
 
+  def AddResponseParameter(self, name, kind, ordinal = None, default = None):
+    if self.response_parameters == None:
+      self.response_parameters = []
+    parameter = Parameter(name, kind, ordinal, default)
+    self.response_parameters.append(parameter)
+    return parameter
+
 
 class Interface(Kind):
   def __init__(self, name = None, peer = None):