Mojo cpp bindings: support Clone() for structs and arrays which don't contain handles.

mojo/public/tools/bindings/pylib/mojom/generate/module.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.
 
 # This module's classes provide an interface to mojo modules. Modules are
 # collections of interfaces and structs to be used by mojo ipc clients and
 # servers.
 #
 # A simple interface would be created this way:
 # module = mojom.generate.module.Module('Foo')
@@ skipping 403 matching lines @@
 def IsAnyHandleKind(kind):
   return (IsNonInterfaceHandleKind(kind) or
           IsInterfaceKind(kind) or
           IsInterfaceRequestKind(kind))
 
 
 def IsMoveOnlyKind(kind):
   return IsObjectKind(kind) or IsAnyHandleKind(kind)
 
 
+def IsCloneableKind(kind):
+  def ContainsHandles(kind, visited_kinds):
+    if kind in visited_kinds:
+      # No need to examine the kind again.
+      return False
+    visited_kinds.add(kind)
+    if IsAnyHandleKind(kind):
+      return True
+    if IsAnyArrayKind(kind):
+      return ContainsHandles(kind.kind, visited_kinds)
+    if IsStructKind(kind):
+      for field in kind.fields:
+        if ContainsHandles(field.kind, visited_kinds):
+          return True
+    return False
+
+  return not ContainsHandles(kind, set())
+
+
 def HasCallbacks(interface):
   for method in interface.methods:
     if method.response_parameters != None:
       return True
   return False