Improve handling of ArrayBuffers in composite objects.

tools/json_schema_compiler/cpp_type_generator.py

Index: tools/json_schema_compiler/cpp_type_generator.py
diff --git a/tools/json_schema_compiler/cpp_type_generator.py b/tools/json_schema_compiler/cpp_type_generator.py
index 1a1821d96084fae325167821115e07d6a1431c9d..1de8d16ebc2388d83304e16477560abdc7991b0c 100644
--- a/tools/json_schema_compiler/cpp_type_generator.py
+++ b/tools/json_schema_compiler/cpp_type_generator.py
@@ -119,6 +119,7 @@ class CppTypeGenerator(object):
     optional.
     """
     cpp_type = None
+    force_wrapping = False
     if prop.type_ == PropertyType.REF:
       dependency_namespace = self._ResolveTypeNamespace(prop.ref_type)
       if not dependency_namespace:
@@ -156,13 +157,17 @@ class CppTypeGenerator(object):
       cpp_type = cpp_type % self.GetType(
           prop.item_type, pad_for_generics=True)
     elif prop.type_ == PropertyType.BINARY:
+      # Since base::BinaryValue's are immutable, we wrap them in a scoped_ptr to
+      # allow them to be modified after the fact.
+      force_wrapping = True
       cpp_type = 'base::BinaryValue'
     else:
       raise NotImplementedError(prop.type_)
 
     # Enums aren't wrapped because C++ won't allow it. Optional enums have a
     # NONE value generated instead.
-    if wrap_optional and prop.optional and prop.type_ != PropertyType.ENUM:
+    if force_wrapping or (wrap_optional and prop.optional and prop.type_ !=
+                          PropertyType.ENUM):
       cpp_type = 'scoped_ptr<%s> ' % cpp_type
     if pad_for_generics:
       return cpp_type